Background & Aim: Recent epidemiologic surveys have demonstrated that the use of, and dependency on, licit and illicit substances is widespread in world population. Approximately %48 of the global population is current consumers of alcohol, whereas %4.5 are current users of illicit drugs. Variant factors such as socio-economic, biological, familial, cultural and … are most cause’s of substances abuse. Therefore the aim of this study was detection of reasons of addiction to narcotic substances from addicts' point of view.
 Material and Methods: In this descriptive-cross sectional study 360 clients were selected continually, from the treatment centers of addiction. A two part questionnaire was employed to collect data about addict’s demographic characteristic and their opinions about the causes of addiction. The reliability and validity of the questionnaire was determined by test-re-test(r=0.92) and validation of it’s contents, Then the Collected data was analyzed using descriptive statistics.
 Results: The results showed that among personal factors physical enjoyment (%64), among familial factors wrong relationship between the parents (%41), of economic factors existing rules in this connection to narcotic substances trade (%52.8), in social factors living in places that narcotic substances are found abundantly (%57.8) and finally among psychological factors easy access to narcotics were reported as important factors for having tendency to narcotics abuse.
 Conclusion: The findings of the study and considering the severe correlation among sociocultural and narcotic substance abuse, necessity of exact planning for war on this calamity is necessary.