Introduction: Retention in a Methadone Maintenance Treatment Program (MMTP) is predictive of abstaining from heroin and has other benefits. Many individuals leave treatment before they experience these positive outcomes. Objective: This research project targeted MMTP drop-outs with an intervention designed to assist them in returning to drug treatment. Methods: Subjects who had left MMTP within the prior 12 months were randomly assigned to intervention or comparison groups. The 3-month long intervention consisted of street outreach, cognitive behavioral groups, and individual counseling. Data were analyzed for 175 subjects who were out of treatment at baseline and who returned for a 6-month follow-up interview (Intervention group, N=111; Comparison group, N=64). Results: A total of 87% of subjects assigned to the intervention condition participated in at least one component. Intervention subjects who attended two or more cognitive behavioral group sessions were more likely than those who attended 0-1 sessions or those in the comparison group to have returned to treatment during the 6 month follow up time period (72 vs. 53 vs. 50%, respectively, P<0.05, chi square test). Conclusion: MMTP drop-outs need not be lost to the drug treatment system if special efforts are made to engage them in interventions developed to encourage treatment re-entry.