The present study attempts to shed light on methadone maintenance patients expectations regarding withdrawal symptoms during voluntary methadone detoxification. The study includes two groups of subjects; one group who have tried on their own initiative to terminate their methadone maintenance treatment (Group 1) and one group that contains rehabilitated patients who have not tried to quit using methadone (Group 2). Two main results have emerged. Group 1 has negative expectations beforehand about the intensity of withdrawal which significantly exceed the later, actual experience. Group 2 has negative expectations about the intensity of withdrawal that significantly exceed the negative expectations of Group 1. The clinical implications of these results are discussed.