While maintained on methadone, heroin users reduce their heroin use and related criminal activity and increase their legitimate employment. These benefits are obtained at the cost of continued opioid dependence. Furthermore, as a consequence of neural adaptation and conditioning, methadone maintenance may impede eventual recovery from opioid dependence. The authors attempt to assess such a possible effect by comparing long-term outcomes after methadone maintenance with those after drug-free treatment. In five long-term follow-up studies of methadone maintenance, the percentages found voluntarily abstinent ranged from 9 to 21. In six long-term follow-up studies of drug-free treatment, the percentages found voluntarily abstinent ranged from 10 to 19. These rates seem remarkably similar. They do not suggest that methadone maintenance impedes eventual recovery from opioid dependence, but they do not clearly exclude such an effect.