Contingency management (CM) is an empirically supported intervention for substance dependence, but it has not been evaluated systematically in non maintained opioid-dependent patients. This retrospective analysis examined whether CM was effective in opioid-dependent patients initiating intensive outpatient psychosocial treatment. In the primary trial (Petry, N. M., Weinstock, J., & Alessi, S. M. ... [Show full abstract] . A randomized trial of contingency management delivered in the context of group counseling. Journal of Consulting and Clinical Psychology, 79, 686-696), substance-abusing patients (n = 239) at two community-based clinics were randomized to standard care (SC) or SC with CM for 12 weeks; in the CM condition, patients earned opportunities to win prizes for attending treatment and submitting drug-negative samples. For this analysis, patients were further classified as non-opioid-dependent (n = 159), opioid-dependent and not receiving maintenance therapy (n = 33), or opioid-dependent and on methadone or Suboxone maintenance therapy (n = 47). Main effects of opioid dependence/maintenance status, treatment condition, and their interaction were evaluated with respect to attendance and abstinence outcomes. Opioid-dependent patients receiving maintenance pharmacotherapy attended treatment on fewer days and achieved less abstinence than their opioid-dependent counterparts who were not on opioid agonist therapy, with Cohen's d effect sizes of 0.63 and 0.61 for attendance and abstinence outcomes, respectively. Nonmaintained opioid-dependent patients evidenced similar outcomes as substance abusing patients who were not opioid-dependent. CM also improved retention and abstinence (d = .26 and .40, respectively), with no interaction effects with opioid dependence/maintenance status noted. These data suggest that CM may be an effective psychosocial intervention potentially suitable for the growing population of opioid-dependent patients, including those not receiving maintenance pharmacotherapy. (PsycINFO Database Record (c) 2013 APA, all rights reserved).