More commonly known under the name of E.P.O, erythropoeitin is a hormone secreted by the Kidneys. It has recently been reproduced synthetically in the form of a drug. For athletes who use it, it stimulates their production of red blood cells allowing them to increase their capacity to intake oxygen.It has therefore become the main performance-enhancing drug used by certain groups of athletes. It is said to be undetectable in urine and blood samples and thus facilitates cheating.However, this drug is dangerous and can cause heart failure for athletes who take it in strong doses (e.g., cyclists).During the Sydney 2000 Games, the IOC Medical Commission gave itself the means to hunt EPO down. Some 2700 tests were carried out, 300 of them specifically for EP, on samples of urine and blood. All medal-winners were tested automatically. Eleven athletes, two of them Olympic champions, tested positive. One had used anabolic steroids, the other a banned substance contained in a cold remedy.