Background. Heroin addiction is a problem with individual, social and economic aspects. The main aim of addiction treatment is to achieve and maintain remission. Secondary aims of the present study have been to determine the factors affecting remission in individuals who applied for treatment to counteract heroin addiction and determine whether family function is effective on remission. Methods. The study included 199 patients who were admitted to the alcohol and drug addiction treatment centre for the first were diagnosed with opioid addiction. The sociodemographic data form and Family Assessment Device (FAD), which shows family functions, were both applied. The patients who were included in the study were evaluated for their continuation of treatment month by month, and for opioid use during the first year of treatment. As a remission criterion valid for at least 1 month of treatment, the criteria adopted for addiction or misuse were not met, and the substance metabolite had to give a negative result in the urine analysis. Results. Inverse correlation was found between the amount of heroin used and remission (p = 0.008). The communication subscale score of FAD was found to be higher in non-working individuals compared with working ones, though the difference was not statistically significant (Z= 2.06 p=0.03). FAD's behavioural control subscale score is higher in men. In the group of those showing a history of disciplinary penalties at school, the average score of FAD's general functions was found to be higher than in those who did not receive disciplinary punishment (Z=1.98 p=0.04). When the group in remission and the group that continued to use heroin were compared, the general functions subscale score was lower in the group with remission (Z = 2.01 p = 0.04). Conclusions. It is important to consider familial functions in achieving and maintaining remission in heroin addiction. Taking note of the disadvantages of family interactions and taking them into consideration during the treatment process may bring benefits by increasing treatment success.