Eighty-one children previously treated for congenital dislocation of the hip (CDH) before the age of 5 were followed up several years after their treatment, and their psychological adjustment was compared with that of 3 other groups; (i) 44 children who had experienced a single hospital admission of less than a week before the age of 5; (ii) 26 children who had experienced 2 or more hospital admissions, the first being before the age of 5; and (iii) 51 children who had no experience of hospital admission. All 4 groups were similar in composition in terms of sex ratio, age at follow-up, family size, birth order, parental age and social situation. Psychological adjustment was measured by means of Rutter's questionnaires for parents and teachers. In addition, the children completed a Schonell reading test. Both the parental and the teacher's questionnaires selected more disordered children in the CDH group. The CDH group also had a higher total score and more health and behaviour problems than did the single admission group on the parental questionnaire. On the teacher's questionnaire they were more antisocial than the single and no admission groups combined. No significant differences were found on the reading test. While the overall impression is that the CDH group are poorly adjusted, there is some suggestion that it is the younger children who are contributing to this effect.