Doubtlessly one of the major problems in Iran is drug abuse or substance abuse. The transmission of HIV/AIDS has made the problem so complicated that has created an urgent need for a campaign against this awful phenomenon. The objective of this study-that was carried out through the cross-sectional method- is considering the situation of the addict death and the related factors. The target population consists of the corpses of the addicts referred to the Legal Medicine Organization of Tehran during 2007 and 2008. The cadavers were examined in the preliminary stage. The blood, urine and the contents of the gall-bladder, stomach and viscera were collected and sent to the toxicology laboratory to examine and find narcotics metabolites and other drugs. The samples of the brain, heart, lungs, liver and kidneys were sent to the pathology laboratories. All of the extracted data were recorded and analyzed using SPSS software. It was diagnosed that 248 cases (79.7%) out of the total 311 in this study, died of substance abuse. Totally 300 cases were reported as male addicts (96.5%). The oldest and youngest addicts were 49 and 17 respectively. The most frequent drugs used were heroin and combination of heroin and opium. No meaningful difference was observed between the death cause of different groups of drug abusers . It seems that the increase in the population of the substance users is the main cause of frequency changes of the addicts' deaths.