The International Olympic Committee has decided not to impose a blanket ban on all Russian athletes despite evidence of widespread state-sponsored doping.
The decision, which has angered many Rio-bound athletes, is just one of many doping scandals at major sporting events.
Here are a few more:
Who could forget Belarusian Nadzeya Ostapchuk? She "won" the 2012 Olympic shot put title against our very own Valerie Adams but was later exposed for repeated doping offences.
Ostapchuk was stripped of her gold medal is banned from competing at the Rio Olympics.
Then there was cyclist Lance Armstrong, who repeatedly denied taking drugs during his long and successful career. In 2013 he finally confessed in an interview with Oprah Winfrey, admitting he'd used banned performance-enhancing drugs throughout much of his career.
Armstrong said doping had helped him in each of his seven Tour de France victories.
In March, Maria Sharapova revealed she had failed a drug test after the Australian Open, testing positive for meldonium. Sharapova said she had taken medicine containing the drug legally for 10 years, but was unaware of a rule change in January this year.
Sharapova said she was taking the drug to treat a magnesium deficiency and an irregular heartbeat, but the drug's inventor says it also has the effect of optimising oxygen use. She has lost several - but not all - major sponsors as a result of the revelations.
American Marion Jones raced into many history books in 2000 after she won five medals at the Sydney Olympics. She graced the cover of Vogue and became a millionaire, consistently denying the doping allegations which dogged her for years.
In 2008 she swapped her precious medals for metal bars and spent six months in jail after she admitted to using steroids, and to lying under oath.
Dubbed one of the most infamous races in history, Canadian Ben Johnson broke the 100m world record for the first time, winning gold at the 1987 World Champs in Rome.
The next year he stopped the clock at 9.79 seconds at the Seoul Olympics but three days later he tested positive for steroids.
In 2013 he took a run at redemption, fronting a campaign to stop doping.