Objective: The natural course of prescription opioid use disorder has not been examined in longitudinal studies. The current study examined correlates of opioid abstinence over time after completing a treatment trial for prescription opioid dependence. Methods: The multi-site Prescription Opioid Addiction Treatment Study (POATS) examined different durations of buprenorphine-naloxone and different intensities of counseling to treat prescription opioid dependence, as assessed by DSM-IV; a longitudinal study was conducted following the clinical trial, from March 2009-January 2013. At 18, 30, and 42 months after treatment entry, telephone interviews were conducted (N=375). In this exploratory, naturalistic study, logistic regression analyses examined the association between treatment modality (including formal treatment and mutual help) and opioid abstinence rates at the follow-up assessments. Results: At the three follow-up assessments, approximately half of the participants reported engaging in current substance use disorder treatment (47-50%). The most common treatments were buprenorphine maintenance (27-35%) and mutual-help group attendance (27-30%), followed by outpatient counseling (18-23%) and methadone maintenance (4%). In adjusted analyses, current opioid agonist treatment showed the strongest association with current opioid abstinence (ORs=5.4, 4.6, and 2.8 at the three assessments), followed by current mutual-help