The discovery of heroin and the development of heroin abuse are introduced. Heroin, the hydrochloride of diacetylmorphine, was discovered by acetylation of morphine. Heroin, in pharmacological studies, proved to be more effective than morphine or codeine. The Bayer Company started the production of heroin in 1898 on a commercial scale. The first clinical results were so promising that heroin was considered a wonder drug. Indeed, heroin was more effective than codeine in respiratory diseases. It has turned out, however, that repeated administration of heroin results in the development of tolerance and the patients become heroin-addicts soon. In the early 1910s morphine addicts "discovered" the euphorising properties of heroin and this effect was enhanced by intravenous administration. Heroin became a narcotic drug and its abuse began to spread quickly. Restrictions on its production, use and distribution were regulated by international treties. The total ban on heroin production was also proposed. As a result of the strict regulations the production and cosumption of heroin showed a significant decrease after 1931. At the same time the underworld recognized the shortage of heroin and started the illicit production and trafficking. The quantity of heroin seized by law enforcement agencies in the past decades rose gradually. As an indicator of the worldwide heroin market, the quantity of confiscated heroin underwent a tenfold increase since 1970. The paper surveys the most important heroin-producing and trafficking countries. Heroin, prepared in clandestine ("kitchen" or "jungle") laboratories, is diluted ("cut") by every member of the illegal heroin distributing chain, i.e. smugglers, traffickers, dealers and vendors.