BACKGROUND: Although depression is a significant psychiatric condition of childhood and adolescence and those with a chronic medical problem are at increased risk for developing depression, the prevalence of depression in children and adolescents undergoing heart and heart-lung transplantation has not been addressed. However, the role of psychosocial factors, such as mood state, in determining outcome is being increasingly acknowledged. METHODS: The Mood and Feelings Questionnaire, a rating scale of depressive symptoms, was administered to 58 children before transplantation and to 46 children after transplantation, with 24 completing both assessments. To compare children’s and parents’ ratings, both child and parent versions, with corresponding items, were utilized. RESULTS: Pre-transplant, the mean score on the child measure was significantly higher (p < 0.001) than that on the parent measure, with 24% and 21% on the child and parent measures, respectively, obtaining scores indicative of depression. Parents of children with acquired heart disease rated their children as having significantly more depressive symptoms than parents of children with congenital heart disease or cystic fibrosis. After transplantation, there was a reduction in mean scores on both the child and parent questionnaires and the pre-transplant differences between the different diagnostic groups were no longer apparent. Over time the numbers obtaining scores indicative of depression decreased by approximately 50%. CONCLUSIONS: Transplantation is associated with a reduction in the prevalence of depressive symptomatology. The role of original diagnosis in the manifestation of depression both before and after transplantation requires further investigation.