Abstract Aims This study investigates factors associated with abstinence, lapse or relapse to heroin use after residential treatment and, specifically, the extent to which changes in cognitive, avoidance and distraction coping responses were related to heroin use and other drug use outcomes. Design, setting, participants The sample comprised 242 clients from 23 residential programmes in the NTORS project, who used heroin before treatment and who were followed-up after treatment during the first 12 months of the study. Measurements Data on client characteristics and problems, coping responses, drug use and other outcomes, were collected by structured face-to-face interviews. Findings Many clients (60%) used heroin after treatment, with the first occasion of heroin use usually occurring very soon after leaving treatment: 40% remained abstinent from heroin. Analyses were conducted for three groups based upon heroin outcome status (abstinent, lapsed, relapsed). Clients who avoided a full relapse to heroin use (abstinent and lapse groups) consistently made more use of cognitive, avoidance and distraction coping strategies at follow-up than at intake. Treatment completion was related to better outcome. The lapse and relapse groups reported higher rates of use of illicit drugs other than heroin after treatment than the abstinent group. Conclusions Despite generally satisfactory drug use outcomes, the lapses and relapses to heroin use give rise to concern. Treatment services should develop further and strengthen relapse prevention and relapse coping skills among drug misusers.