As the control regarding traditional doping agents like stimulants and anabolic steroids has become more effective, athletes who want to dope seek other means to improve performance. Doping control has traditionally relied primarily on detecting banned exogenous substances in urine samples, and therefore an obvious way to go is to apply endogenous substances that cannot be deteted in such samples, at least by the methods applied today. Such doping methods include blood doping (intravenously infusing one's own or donated blood into an individual to induce erythrocytaemia) and the misuse of commercially available recombinant peptide hormones like ely-thropoietin (EPO) and growth hormone (GH)(13.18, 14). This development has led many athletes, team physicians and sport administrators to urge for new methods applicable in doping control, including blood sampling (10).

In cross-country skiing, the International Skiing Federation (FIS) used blood sampling as a part of doping control during last year's World Championships, checking for non-autologous blood doping (19). The lnternational Amateur Athletic Federation (IAAF) decided to include blood sampling in doping control during eight World Cup meetings in 1993 and 1994. to have an effective control against non-autologous blood doping and to gain experience from a wide variety of analyses aiming at detecting the application of GH, EPO and testosterone. In the present study we report the results from analysing blood samples from 99 athletes tested during these lAAF meetings.