A few organizations have tried to estimate the costs of illicit drugs in Iran and DHCQ has published some information on this issue. Yet these studies have not been conducted in a systematic way with a rigorous methodology. A few organizations have tried to estimate the costs of illicit drugs in Iran and DHCQ has published some information on this issue. Yet these studies have not been conducted in a systematic way with a rigorous methodology. Subsequent to reviewing earlier estimations, this article uses cost-paying social groups at the macro level and LEWIN’s method at the micro level to estimated the costs illicit drugs incurred to different groups of users and non-users (the society) and the government. Costs are divided in three parts (direct costs, indirect costs and peripheral costs), each of which is classified.