The clinical data and development of 8 cases with subependymal cysts detected on neurosonography in the neonatal period were studied, and the prognosis was found to vary. Also, clinico-pathological examination of 15 autopsied cases of congenital subependymal cysts (SEC) was performed, with immunohistochemical staining involving neuron-specific enolase in three cases, which revealed that congenital SEC are often complicated by various degrees of brain and heart anomalies, and suggested that SEC might occur in a wide gestational age range, with various causes. Therefore, it is important in the future to determine the agents which cause destruction of the subependymal germinal matrix.