OBJECTIVE: In-treatment and post-treatment outcomes were compared for three detoxification procedures (lofexidine+naloxone, lofexidine+placebo naloxone, and methadone). SAMPLE AND DESIGN: The sample was 137 opiate dependent in-patients. Detoxification treatments were 6-day lofexidine+naloxone (n=45), lofexidine+placebo naloxone (n=46), or 10-day methadone reduction (n=46). A cohort study design was used with double-blind random allocation to lofexidine+naloxone versus lofexidine+placebo. Patients who did not consent to, or who were excluded from randomisation received methadone. RESULTS: Outcome differences between treatment groups at follow-up were generally associated with length of stay post-detoxification rather than detoxification procedure. Among patients who were not opiate abstinent throughout follow-up (n=85), those who received lofexidine+naloxone detoxification reported a longer interval to first heroin use, with an interaction between detoxification medication and subsequent retention in treatment also identified. CONCLUSIONS: Detoxification medication may influence medium-term opiate use outcomes via its effect upon retention in treatment.