As a part of a larger study, 75 consecutive patients with conduct disorder (48% men, median age 15, range: 6-19 years) were followed up after 18-21 years (mean: 19) with a clinical interview using DSM-III criteria. At follow-up, 47% had no Axis I disorder, 24% an anxiety disorder, 25% a substance abuse disorder and only one a psychotic disorder. Thirty-three percent fulfilled the criteria of an antisocial personality disorder. An additional anxiety disorder at the time of the primary examination was a strong predictor of a poor outcome, as was also criminal offences. The study shows the severe prognosis of conduct disorder and the importance of this disorder as an antecedent to substance abuse. However, since nearly half of these patients developed into a healthy state during the 20-year follow-up period, work should be continued to develop better treatment for these patients.