The purpose of this study was to investigate the prognosis of intraventricular haemorrhage (IVH) in term infants and its prevention and treatment. The authors diagnosed IVH in full-term newborns by using computerized tomography (CT) or cranial ultrasonography (US). The results of CT or US were reviewed and the grade of haemorrhage was determined by an independent radiologist using Papile's criteria. All the infants were examined on the first day of their life by a paediatrician and judged to be full term. Survivors were examined between age 2 and 10 years at the Child Development Clinic by a Developmental Paediatrician using the Gesell scales and a standard neurologic examination. The results showed that three of 36 infants (8 per cent) died; complications of pregnancy were present in 17 mothers (47 per cent); nine women tested negative for platelet antigen 1 and their infants exhibited alloimmune thrombocytopenia. Age at diagnosis ranged from in utero to 28 days. Clinical presentation included feeding intolerance, irritability, jaundice, fever, and restlessness. Of the nine children with grade IV IVH, three died and six survivors were severely handicapped. Overall, 22 (67 per cent) of 33 survivors had no or mild handicap. The results of this study suggest that severity of haemorrhage was of prognostic value. Perinatal alloimmune thrombocytopenia turned out to be the single most important cause of severe haemorrhage and poor outcome. Identification and treatment of these infants must begin in utero if we are to prevent IVH and its complications in this group of patients.