The study will measure the number of patients who successfully accept referral and initiate substitution treatment for heroin dependence, comparing patients in intervention arm to patients in the control condition (RCT design). Also, as a secondary outcome measure, retention and treatment outcome (substance use and clinical characteristics) will be compared between the two groups. In addition, this study will enable a number of sub-analyses aiming to increase knowledge about heroin addicts' detailed substance use pattern and clinical characteristics. Patients will be followed with respect to retention, substance use and clinical picture for three years.