OBJECTIVE: The aim of this article is to investigate the impact of a child's severe congenital heart disease on the family and to prospectively examine the influence of disease specific and psychosocial factors on the family. DESIGN: A prospective cohort study. PATIENTS: Parents of 104 infants who had undergone cardiopulmonary bypass surgery before the age of 12 months for congenital heart disease were included. INTERVENTIONS: None. OUTCOME MEASURES: Parents completed the generic Impact on Family scale and a social support questionnaire; a large number of medical data were extracted from the patients' hospital records. RESULTS: Parents most frequently reported that they were thinking about not having more children and living on a "roller coaster." No difference was found in the total Impact on Family scale score between fathers and mothers. The presence of a genetic disorder in the child and lower levels of perceived social support was significantly associated with a greater impact on the family. CONCLUSIONS: The impact of an infant's congenital heart disease on the family is determined both by child's medical condition and family's psychosocial factors. Families with poorer social support network may have the greatest need for professional interventions, especially if their child has an underlying genetic disorder.