There will be random testing for some 500 players on the PGA Tour's three circuits and sanctions that include a lifetime ban for the third offense.
The tour will not say who gets tested and when, although it had its first customer Wednesday morning -- PGA Tour commissioner Tim Finchem, who had his executive staff also go through the process.
Tiger Woods remains eligible for testing even though he had season-ending surgery on his left knee last week. Woods said he has tested himself twice, the second time because he changed the brand of the amino acid in his nutritional program. He said both tests came back clean.
"All we have to test is one guy," Steve Stricker said, alluding to Woods. "Because we can't beat him, anyway."
Finchem has said for most of this decade that he does not know of a performance-enhancing drug for golf, but the sport came under increasing pressure in the wake of scandals in other sports.
Plus, it must have an anti-doping program in place if it wants to be part of the Olympic program in 2016.
"I don't think our sport needs it," Kenny Perry said. "But if they feel like we need to be like baseball and all the other sports, that's fine with me. I don't think you'll see any problems on our tour. I haven't seen any in my 22 years out here. Maybe somebody did take steroids or whatever, but I don't think you'll see it as an issue."
Drug testing also began this week on the European PGA Tour, while the LPGA Tour began its program at the start of the season. The British Open will not test for drugs until next year.
Sanctions range from one year for the first offense, five years for a second offense and a permanent ban after that.