Self-reported dysphoria, personality disorder traits, and subjective opioid withdrawal symptoms were assessed in 30 opioid abusers before and after a rapid medical detoxification from heroin. Subject exclusion criteria reflected an effort to control for potential sources of affective change that were extraneous to the effect of detoxification. Subjects received few rehabilitative services during their 12-day inpatient hospitalization, and were not permitted visitors or off-ward privileges. At the preadmission assessment, they reported elevated levels of dysphoria and personality disorder traits, as well as opioid withdrawal symptoms. The results indicate that clinically significant declines in symptoms of dysphoria, opioid withdrawal symptoms, and personality disorder traits occur during the course of a rapid medical detoxification. Dysphoric and opioid withdrawal symptom abatement was most pronounced between the preadmission and admission assessments. These factors should be considered in the clinical diagnosis and treatment, as well as in research about psychiatric comorbidity of these substance abusers.