The program was developed due to significant increases in problems associated with the use of illegal drugs, particularly in heavily addicted intravenous drug users. It reflected the Swiss drug policy of repression, prevention, treatment, and harm reduction. The Swiss law on narcotics provides the legal basis for the program, which involved a multicenter research trial. The research involved a double-blind design with randomized prescription of heroin, morphine, and methadone in several cities, individualized prescription of these drugs in one city, and individualized prescription in a treatment project serving female drug abusers. Participants are admitted on the basis of a comprehensive assessment procedure and are involved in weekly counseling. Preliminary observations during the first 9 months indicate that this approach may be effective for some addicts, although many questions, particularly regarding long-term effects, still require answers. Table, figures, and 20 references