Turkey has continuously experienced problems with abuse of, and addiction to, opium derivatives. In this study, we analyzed the relationship between heroin overdose deaths and the characteristics of seized opium derivatives. Data were gathered from the Council of Forensic Medicine of the Ministry of Justice in Istanbul from 1990 to 2000. There were 636 heroin-related deaths during this period, 595 of which were classified as heroin overdose deaths. Mean crude and weighted heroin purities remained relatively constant and were calculated to be 46% (57-34%) and 51% (39-59%), respectively. The weight of heroin and the number of heroin seizures, but not the heroin purity, were significantly associated with the number of heroin-related deaths. Prevention strategies are needed to reduce the number of deaths caused by overdoses in countries situated on drug trafficking routes. These strategies should focus on drug trafficking, by providing increased levels of, and support for, law enforcement, stopping the supply of precursor chemicals, and combating corruption among border officials.