Autopsy records from the Women and Infants' Hospital from January 1974 through January 1994 were reviewed to identify cardiac malformations in the presence of skeletal dysplasia. Of 24 cases of lethal fetal or neonatal osteochondrodysplasias, 4 were given diagnoses in which disorders of type II collagen are regarded as causative. These 4 were categorized in the spondyloepiphyseal dysplasia (SED) spectrum of disorders; specifically two patients with hypochondrogenesis and two with spondyloepiphyseal dysplasia congenita were identified. Defects in cardiac septation were noted in the 2 patients with hypochondrogenesis. No cardiovascular abnormalities were present in the remaining cases, which included thanatophoric dysplasia, osteogenesis imperfecta, and asphyxiating thoracic dystrophy. Although cardiovascular malformations have been described in other types of osteochondrodysplasias, e.g., short rib polydactyly syndrome type II and chondroectodermal (Ellis-van Creveld) dysplasia, congenital heart disease has not been described in hypochondrogenesis. Type II collagen, which has been found to be abnormal in some patients with hypochondrogenesis, is considered to have a limited tissue distribution, and has not been detected as yet in human myocardium. The findings presented here suggest that type II collagen may function in human cardiogenesis.