In this paper five follow-up studies about heroin-addicts are discussed. The period between first admission and follow-up was at least 10 years. The studies were done in different decades and in different large cities in Western society. Ten years after first admission 40% was abstinent of drugs, 15% died of the effects of the addiction and 40% was still addicted to heroin. Retrospectively one cannot discriminate prognostic favourable factors. About the effect of therapy one cannot draw definit conclusions. In one study imprisonment longer than 9 months, followed by parole and `strong community supervision' correlated in 20 out of 30 cases with abstinence.