Drug addiction is linked with increased prevalence of various illnesses. Of major importance are skin diseases which often have a powerful influence on the health. Analysis of the situation in Switzerland at the outset of the 1990s showed that not all drug addicts could be reached with the existing range of treatments. For this reason, heroin-supported treatment was examined as a new therapy option from 1994 on. The influence on the skin's health are examined in this study. The minimum age of those admitted was set at age 20. Heroin addiction had to date back at least two years, and several treatment efforts had to have failed. Data of 1,035 patients was based on tests at admission and after six, 12, and 18 months of treatment. Some 18% of drug consumers indicated abcesses at admission, and almost 30% showed phlegmones. The prevalence of all skin diseases examined show significant declines over the 18 months of treatment. The relative risk resulting from puncture points fell to 0.35 (SD: 0.26-0.47), from phlegmones to 0.24 (SD: 0.14-0.41), from absesses to 0.31 (SD: 0.15-0.60). This study shows that skin diseases are a frequent and important complication among intravenous drug addicts. Heroin-supported treatment led to favourable progress of the dermatological situation among patients.