10 Biggest Baseball Scandals of All Time: Cheating, Gambling & More
Updated September 25, 2026
Updated September 25, 2026
Baseball has been around for more than 150 years, and not all of its history has happened between the lines. The sport has dealt with game-fixing, gambling, performance-enhancing drugs, sign stealing, collusion and even hacking, with some scandals changing MLB rules and reputations for decades.
Some involved a single player or just a handful of people. Others stretched across a whole team—or the entire league. From the 1877 Louisville Grays to the Black Sox, Pete Rose, the Steroid Era and the 2017 Astros, here are the 10 biggest scandals in baseball history and the stories behind them.
There’s a good chance you’ve never heard of the Louisville Grays, but they were at the center of one of baseball’s earliest major gambling scandals. In 1877, just the second season of the National League, Louisville was 27-13 and leading the race for the NL pennant before going 0-7-1 to start a late-season East Coast road trip.
That collapse raised suspicions, and an investigation eventually connected pitcher Jim Devlin, outfielder George Hall and Al Nichols to gamblers paying players to lose games. Devlin pitched every inning for Louisville that season, and one gambler told him to send the code word “sash” by telegram whenever he was willing to fix a game.
The telegrams became a big part of the investigation. Hall also confessed after seeing Devlin meet with team official Charles Chase and assuming Devlin had already told him everything. Exactly how many National League games were fixed is still unclear, but Hall and Devlin admitted to throwing exhibition games for money.
Louisville eventually expelled Devlin, Hall, Nichols and Bill Craver, and the National League barred all four from its clubs. The scandal helped show early on that the new league wasn't going to tolerate game-fixing, and the Grays never played another season.
This one is unlike just about every other scandal on the list. From 2013 to 2014, Cardinals executive Christopher Correa repeatedly broke into the Astros’ internal database, known as “Ground Control.” It contained everything from scouting reports and player evaluations to draft rankings and private trade discussions.
And it wasn’t some elaborate hacking operation. Correa knew an old password used by a former Cardinals employee who had joined Houston and discovered that a variation of it still worked. He used that access around the MLB Draft and trade deadline, and even after Houston changed its login information, Correa found a way back in by accessing an employee’s email.
Eventually, the FBI got involved. Correa pleaded guilty to five federal charges and was sentenced to 46 months in prison, ordered to pay more than $279,000 in restitution and permanently banned from MLB. Investigators found no evidence that anyone else with the Cardinals was involved.
Still, St. Louis paid a major price. MLB ordered the Cardinals to pay $2 million to the Astros and gave Houston their top two available picks in the 2017 MLB Draft. An MLB executive going to federal prison for hacking another team is what puts this bizarre scandal at No. 9 on our list.
More than 60 years before the Astros were banging on trash cans, the New York Giants (now the San Francisco Giants) had their own sign-stealing system. In 1951, manager Leo Durocher’s team used a telescope positioned beyond center field at the Polo Grounds to spy on opposing catchers and figure out which pitch was coming.
The stolen sign was then sent by an electrical buzzer to the Giants’ bullpen. One buzz meant fastball, while two meant an off-speed pitch. A player in the bullpen would then signal the hitter. The system began in July, and the Giants eventually erased a 13½-game Dodgers lead to force a playoff for the NL pennant.
That's where this scandal gets really interesting. In the deciding game, Bobby Thomson hit a three-run walk-off homer off Ralph Branca to win the pennant, creating the famous “Shot Heard 'Round the World.” The sign-stealing system was operating that day, and bullpen catcher Sal Yvars later said he relayed the fastball sign before Thomson's homer. Thomson, however, maintained that he didn't use a stolen sign on that pitch.
The full story didn't become public until 50 years later, when surviving Giants confirmed details of the scheme in 2001. Nobody was punished and the Giants kept their 1951 NL pennant, but the revelation added a completely different layer to one of baseball's most famous moments—and puts their telescope-and-buzzer scheme at No. 8 on our list.
The Biogenesis scandal started with a small anti-aging clinic in South Florida and a $4,000 dispute. After a falling out with clinic founder Anthony Bosch, former employee Porter Fischer took boxes of records that eventually reached the Miami New Times. When the newspaper published its investigation in January 2013, the documents connected some of baseball's biggest names to performance-enhancing drugs.
MLB launched its own investigation, and the case really broke open when Bosch agreed to cooperate with the league. Ryan Braun, the 2011 NL MVP, was suspended for 65 games in July. Two weeks later, MLB disciplined 13 more players, including Nelson Cruz, Jhonny Peralta and Alex Rodriguez.
A-Rod quickly became the face of the scandal. MLB initially suspended him for 211 games for his connection to Biogenesis and attempts to obstruct the investigation. Rodriguez fought the punishment, but an arbitrator ultimately banned him for the entire 2014 season and postseason, costing him more than $22 million in salary.
The fallout extended beyond baseball. Bosch later pleaded guilty to a federal charge related to distributing testosterone and was sentenced to four years in prison. Between the mass suspensions, the stars involved and A-Rod losing an entire season, Biogenesis became one of MLB's biggest PED scandals after the Steroid Era.
Players buying cocaine during games. Dealers getting access to MLB clubhouses. Even the Pittsburgh Pirates' mascot getting caught up in the scandal. That's what came out in federal court in 1985, when several current and former MLB players were given immunity to testify about cocaine use around baseball.
The group included stars like Keith Hernandez and Dave Parker. Hernandez estimated that as many as 40% of MLB players were using cocaine around 1980, although he later acknowledged that number could have been well off. Parker admitted to years of cocaine use and arranging purchases for other players, while former Pirate John Milner testified that he once bought cocaine inside Three Rivers Stadium during a game.
The investigation led to convictions for several drug dealers, while MLB disciplined 21 players in 1986. Seven initially received one-year suspensions, but they could keep playing by donating part of their salaries to drug programs, performing community service and agreeing to drug testing.
More than anything, the Pittsburgh trials showed that baseball's cocaine problem went far beyond a few players using drugs away from the ballpark. With stars, dealers and even MLB clubhouses tied to cocaine, it became one of the biggest off-field scandals baseball had faced.
Imagine being one of the best players in baseball, becoming a free agent and suddenly finding out that almost nobody wants to sign you. That's what started happening in the mid-1980s, when MLB owners worked together to suppress the free-agent market and keep player salaries from rising.
The effects were hard to miss. After the 1985 season, 29 of 33 free agents ended up back with their original teams. A year later, stars like Tim Raines, Jack Morris and Andre Dawson struggled to find offers. Dawson's situation got so bad that he handed the Cubs a blank contract and let them choose his salary. Chicago gave him a one-year deal with a $500,000 base salary, and Dawson responded by winning the 1987 NL MVP.
The MLB Players Association knew something wasn't right and filed a series of grievances. Arbitrators eventually ruled against the owners in three separate collusion cases, finding that teams had violated the collective bargaining agreement by working together instead of making independent decisions on free agents.
The scheme ended up costing the owners far more than they were trying to save. MLB eventually agreed to pay players $280 million to settle the cases, while the scandal further damaged an already tense relationship between players and owners.
Pete Rose finished his career with 4,256 hits, more than anyone in MLB history. But just a few years after his final game, baseball's all-time hits leader was at the center of a gambling investigation that would keep him out of the sport for the rest of his life.
MLB began investigating Rose in 1989, while he was managing the Cincinnati Reds. The investigation uncovered betting records, phone records and witness testimony showing that Rose regularly bet on baseball, including Cincinnati Reds games. Investigators documented 412 baseball bets over roughly three months in 1987 alone. There was no evidence that he bet against Cincinnati, but betting on games he was managing still violated one of baseball's most serious rules.
Rose denied the allegations, but in August 1989 he agreed to be placed on MLB's permanently ineligible list. He continued denying that he had bet on baseball for nearly 15 years before finally admitting in 2004 that he bet on the Reds while managing them.
Even then, Rose insisted he never bet on baseball as a player. That claim took another hit in 2015, when previously hidden betting records seized from one of his associates showed wagers on Reds games in 1986, when Rose was still Cincinnati's player-manager.
Rose remained on MLB's permanently ineligible list until his death in 2024. MLB changed its policy the following year and removed deceased individuals from the list, meaning Rose can now be considered for the Baseball Hall of Fame.
A camera in center field, a monitor near the dugout and a trash can. That was the basic setup behind one of the biggest cheating scandals in modern baseball history.
During the 2017 season, the Astros used the camera feed to see opposing catchers' signs in real time. Players watched the monitor, figured out what pitch was coming and then banged on a trash can to alert the hitter. No bang generally meant fastball, while banging signaled an off-speed or breaking pitch.
The scheme became even more controversial because it continued into the postseason. Houston went on to beat the Dodgers in seven games to win the first World Series title in franchise history, all while the sign-stealing system was still being used.
And for more than two years, they got away with it. That changed in 2019 when former Astros pitcher Mike Fiers went public and explained how the system worked. MLB investigated and confirmed that Houston had illegally used technology to steal signs during its 2017 championship season and into 2018.
The Astros were eventually fined $5 million and lost their first- and second-round picks in both the 2020 and 2021 MLB Drafts, while manager AJ Hinch and GM Jeff Luhnow were suspended and fired. Alex Cora and Carlos Beltrán also lost managerial jobs elsewhere because of their connections to the scheme.
But the players involved weren't suspended, and Houston kept its 2017 World Series championship. That's a big reason the trash-can scandal is still talked about nearly a decade later.
Mark McGwire hit 70 home runs in 1998. Sammy Sosa hit 66. Three years later, Barry Bonds hit 73. Baseball's biggest home run records were suddenly being broken, but steroids soon became just as much a part of the story as the home runs themselves.
MLB had prohibited steroids without a prescription since 1991, but there was no league-wide testing program to enforce the rule. Testing didn't begin until the 2000s, after years of record-breaking performances and growing questions about PED use around baseball.
Those questions reached Congress in 2005, when McGwire, Sosa, Rafael Palmeiro and others were called to testify about steroids. Palmeiro denied using them, only to test positive for a performance-enhancing drug months later. McGwire eventually admitted in 2010 that he had used steroids during his career, including during the 1998 home run chase.
The BALCO investigation and 2007 Mitchell Report revealed even more about PED use, and MLB responded by expanding drug testing and increasing suspensions for positive tests. Bonds still holds the single-season home run record with 73 and the career record with 762, while several stars from the era have spent years on the outside of the Hall of Fame.
Few scandals changed baseball as much as the Steroid Era. It changed how MLB handles PEDs and still affects how some of the biggest records and careers in baseball history are viewed, putting it at No. 2 on our list.
At No. 1 on our list is a scandal that gets to the heart of sports itself: players intentionally trying to lose the World Series. In 1919, eight members of the Chicago White Sox became involved in a scheme with gamblers to fix the World Series against the Cincinnati Reds.
First baseman Chick Gandil helped organize the deal, which called for the players to receive $100,000. Star pitcher Eddie Cicotte was promised $10,000 up front and later admitted that he found the cash underneath his hotel-room pillow before the Series began.
Cincinnati beat Chicago five games to three, but the scandal didn't fully come out until the following year. Cicotte, Shoeless Joe Jackson and others admitted their involvement, and all eight players were eventually indicted on conspiracy charges.
Then came one of the strangest parts of the story. All eight players were acquitted in court in 1921, but baseball commissioner Kenesaw Mountain Landis banned them for life the very next day. That included Buck Weaver, who wasn't shown to have taken money but knew about the fix and failed to report it.
More than 100 years later, players agreeing to lose the World Series for money is still hard to top, making the Black Sox scandal No. 1 on our list.
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