The Essendon Football Club supplements saga (also referred to as the Essendon doping scandal) was a sports controversy which occurred during the early- and mid-2010s. The Essendon Football Club, a professional Australian rules football club playing in the Australian Football League (AFL), was investigated starting in February 2013 by the Australian Sports Anti-Doping Authority (ASADA) and the World Anti-Doping Agency (WADA) over the legality of its supplements program during the 2012 AFL season and the preceding preseason. After four years of investigations and legal proceedings, thirty-four players at the club were found guilty of having used the banned peptide Thymosin beta-4 and incurred suspensions.
The initial stages of the investigation in 2013 made no findings regarding the legality of the supplements program, but highlighted a wide range of governance and duty-of-care failures relating to the program. In August 2013, the AFL fined Essendon $2,000,000, revoked its opportunity to play in the 2013 finals series, and suspended senior coach James Hird and general manager Danny Corcoran as a result of these findings.
The second phase of the investigation resulted in thirty-four players being issued show cause notices by ASADA and infraction notices by the AFL in 2014, alleging the use of Thymosin beta-4 during the 2012 season. After facing an AFL Tribunal hearing in the 2014/15 offseason, the players were initially found not guilty of these offences. That decision was appealed by the World Anti-Doping Agency to the Court of Arbitration for Sport, which returned a guilty verdict on 12 January 2016. The guilty verdict was unsuccessfully appealed in the Federal Supreme Court of Switzerland. The thirty-four players were suspended for two years, affecting seventeen still-active AFL players who missed the 2016 season as a result of the findings.