tumors in children biopsy and autopsy findings obtained at the tartu autopsy department for a 35year period from 1941 to 1975 are analysed within this period tumors in children under 16 years of age were observed in 1183 cases benign tumors 970 were predominating over malignant ones 213 among benign tumors hemangiomas were in the first place and more frequently observed in girls among malignant tumors sarcomas were most frequently detected malignant tumors in girls were as frequent as in boys cardiac disease in methylmalonic acidemia methylmalonic acidemia mma is a heterogeneous disorder with onset from infancy to adulthood and varying degrees of organ involvement and severity cardiac disease is a known lethal complication of other organic acidemias but has not been associated with mma we identified 3 patients with mma and cardiac disease