The study found that heroin weight and the number of heroin seizures were predictors of the trends in the number of heroin deaths over the period studied. There were 636 heroin-related deaths between 1990 and 2000 in Istanbul, Turkey. Although they were mostly overdose deaths (595 cases), 41 were heroin-related suicides, homicides, and accidents. An upward trend in the number of heroin-related deaths occurred between 1990 and 2000. The total weight of seized drugs was approximately 25,000 kg. The year 1996 had the highest quantity of drug seizures, with 3,600 kg; in contrast, 1992 saw the lowest quantity of drug seizures, with 700 kg in total weight. In the same pattern, heroin-related deaths peaked in 1996 (87 deaths), from a low of 25 deaths in 1990. In 1990, the highest rate of weighted purity for heroin was established at 59 percent; the highest ratio of crude purity was 57 percent in 1995; and the weighted purity was recorded at 58 percent in 1995. Apart from these fluctuations, mean crude and weighted heroin purity were relatively stable at 46 percent and 51 percent, respectively, for the 11 years addressed in the study. According to the Prais-Winsten autoregression equation, the heroin weight and number of heroin seizures were significant variables impacting the number of heroin-related deaths between 1990 and 2000 in Istanbul, Turkey. 2 tables, 1 figure, and 19 references