 This retrospective analytical study evaluated forensic toxicology analysis results from 2011 to 2016 in Tehran Province, Iran, finding that a total of 1388 polydrug use associated deaths were investigated during the six-year study period. The victims were mostly young men of 20 to 40 years of age and methadone and amphetamine type stimulants were in the highest category for polydrug use associated deaths. Additionally, opium, tremidol, and tricyclic antidepressants were also commonly used with other drugs in some cases. The study highlights the major role of substance abuse and death. This article was authored by Maryam Akgari, Fariba Sardari Ravani and Masood Gadapasha.