Background: Chronic opioid use is a major public health problem with significant morbidity. The aim of this study was to investigate factors associated with sustained remission among a sample of Iranian chronic opioid users in Shiraz, Iran.Methods: This was a cross-sectional study to evaluate sustained remission among chronic opiate users aged 20-60 years. Participants included two groups: 365 people who have been in sustained remission for the past year, and 187 persons who did not achieve remission for the past one year. Then, demographic and factors related to drug use pattern and previous treatments were compared between two groups. Pearson chi-square test was used for univariate analysis and backward stepwise logistic regression was used to estimate adjusted odds ratios (AORs).Findings: Our findings showed that sustained remission was associated with Narcotic Anonymous (NA) participation [AOR = 3.28, 95% confidence interval (CI): 2.19-4.89, P < 0.001], male gender (AOR = 2.53, 95% CI: 1.45-4.43, P = 0.001), younger age of onset (AOR = 1.63, 95% CI: 1.03–2.58, P = 0.037), higher total years of opioid use (AOR = 2.13, 95% CI: 1.42–3.19, P < 0.001), no history of imprisonment (AOR = 2.11, 95% CI: 1.16-3.85, P = 0.015), and family support (AOR = 2.58, 95% CI: 1.33-5.01, P = 0.005).Conclusion: Participation in self-help groups can be a suitable alternative in predicting sustained remission among chronic opiate users. Chronic opioid users should be encouraged by the physicians who are involved in the treatment of drug addiction to participate in NA programs.