BACKGROUND Drug abuse is a chronic and enduring phenomenon, which is among the important challenging public health problems. One of the main aspects in drug abuse is the relapse. OBJECTIVE The aims of this study were to estimate the time to relapse (survival rate) and to evaluate some of its associated variables by survival analysis. METHODS This research was conducted in four addiction treatment centers on 140 self-referred addicts in Ilam city, Iran, in 2012. Cluster sampling method was used for selecting the samples and data were collected by interview and referring to the subjects' records. The gathered data were analyzed through the life table, Kaplan-Meier analysis, log rank test, and Cox regression. RESULTS The relapse rate was 30.42%, mean and median of the time to relapse (survival time) were 27.40 ± 1.63 months (CI 95%: 24.19 - 30.60) and 25 ± 2.25 months (CI 95%: 22.5 - 27.5), respectively. In the first six months, the cumulative survival rate was 83%, while in the 24th month it was 46% and the following time was consistent. Job status (OR = 2.64), marital status (OR = 1.55), family size (OR = 1.20) and age (OR = 0.23) were statistically significant in Cox regression model. CONCLUSIONS In the initial treatment, it seems necessary to supervise and monitor the treatment process through staff in addiction treatment centers together with the company of the addicts' families to reduce relapse rate.