Martina Hingis was banned for two years Friday for testing positive for cocaine at Wimbledon last year.
The International Tennis Federation said an independent anti-doping tribunal found that Hingis, who announced her retirement Nov. 1 on the day she revealed the positive test, had committed an offense.
The 27-year-old Hingis denied using cocaine, but the tribunal rejected suggestions there were any doubts over her sample.
Although the five-time Grand Slam winner is now retired, Hingis' suspension is backdated to Oct. 1. She has three weeks to contest the ruling and punishment.
The ITF disqualified Hingis' results from last year's Wimbledon and any subsequent tournaments she played in. She also forfeits any ranking points gained and US$129,481 in prize money.
Hingis provided the sample after losing 6-4, 6-2 to Laura Granville in the third round at Wimbledon.
There was no immediate reaction from Hingis, who dominated women's tennis between 1997-2000 by winning three straight Australian Opens, Wimbledon and the U.S. Open. She was twice a runner-up at the French Open where her loss to Iva Majoli in 1997 stopped her winning all four Grand Slams that year.
Hingis returned to the sport in 2005 after a four-year absence because of injuries.
When announcing her retirement at a news conference in Zurich, Hingis denied ever using cocaine.
"I find this accusation so horrendous, so monstrous that I've decided to confront it head on by talking to the press," she said. "I am frustrated and angry. I believe that I am absolutely 100 percent innocent."
Larry Scott, chief executive of the WTA Tour, said Friday his organization was saddened by the outcome of the case.
"As a signatory to the WADA Code and a founding member of the Tennis Anti-Doping Program, the WTA Tour is committed to ensuring the integrity and competitive fairness of women's professional tennis, and ensuring the heath and well-being of our athletes," Scott said.
"We are saddened by this news as Martina has meant so much to fans the world over and made many positive contributions to the sport."