A study was made of 26 adolescents, aged from 13 to 18 years, with different types of severe congenital heart disease, assessing their somatic condition and its impact on mental health and psychosocial functioning. Physical capacity was reduced, more pronounced in girls than in boys, along with an increased rate of psychiatric problems. Associations were found between physical capacity and psychosocial functioning, and between psychosocial functioning and chronic family difficulties. On the other hand, half the patients studied achieved fair function, both physically and with regard to their mental health. The degree of reduced physical capacity is an important etiological factor for impaired mental health in patients with congenital heart disease. This knowledge should be taken into account when dealing with this group of patients. A good social network seems to be a protective factor. It will probably be rewarding to give patients and their families not only an optimal medical follow-up, but also psychological, practical and financial support to improve or create such a network.