Thirty-five individuals aged 17 to 24 in whom severe chronic hyperactivity had been diagnosed 10 years before were studied together with 25 matched controls. There were no significant differences in mean height or weight or in electroencephalographic findings, but the mean pulse rate was significantly higher in the hyperactive group. Cognitive style tests indicated continued difficulty in reflection (resulting in more errors) but less impulsivity (longer reaction time) in the hyperactive individuals. Compared with controls, hyperactive subjects were continuing to have more scholastic difficulty, although this difference seemed to be less pronounced than 5 years before. Their adjustment in work situations and living arrangements did not differ significantly from that of the controls. Restlessness, both reported and observed, continued to be a problem for the hyperactive individuals, and socialization skills and sense of well-being continued to be poorer than in the controls. The hyperactive individuals did not show significantly more antisocial behaviour, nonmedical use of drugs or serious psychiatric disturbances.