Dropout and recidivism from addiction treatment has been found to be associated with individuals' readiness for change. Motivation for treatment among participants entering the North American Opiate Medication Initiative (NAOMI) randomized controlled trial, which compared heroin assisted treatment (HAT) to optimized methadone maintenance treatment (MMT), was assessed. Through multivariate regression, we aimed to determine whether baseline motivational status was predictive of four treatment outcomes: early dropout, 12-month retention, 12-month response to treatment, and time to discontinuation of treatment. Among the 251 out-of-treatment chronic opioid dependent patients recruited in Montreal, Quebec and Vancouver, British Columbia, 52% reported having a high level of motivation for treatment. HAT was statistically significantly more effective than MMT on each of the outcomes assessed. Baseline motivational status did not predict retention or time to discontinuation in either HAT or MMT. However, while patients were retained in HAT regardless of motivational status, motivated patients showed a more favourable response to treatment in terms of decreases in crime and illicit drug use. These results suggest that HAT successfully retains opioid dependent patients who otherwise may not have been attracted into existing treatment options, and may enhance the odds of successful rehabilitation among patients motivated for treatment.