Postoperative reactions of children and adolescents realistically prepared for cardiac surgery were analysed for acute and long-term responses. No cases of delirium or psychoses occurred in the 60 children while they were in hospital. Fifty sets of parents and children answered questionnaires 6 months to 4 years after operation (36 under 1 year, 8 from 1 to 3 years, and 6 over 3 years) and assessment of these showed only long-term reaction. Evaluation of reactions is presented by age and in detail. The children aged 2 to 7 years had the greatest number of negative reactions and the only long-term reaction also came from this group. Children 8 to 11 years of age had the least number of negative reactions and the highest number of positive gains. Adolescents, 12 to 19 years of age, were often concerned with their body image (wanted to be considered 'well', resented the scar, etc). From the standpoint of emotional stability and after effects, the 8 to 11-year-old group seemed to do best.