Eighteen of 68 infants born over a 4-year period who had cranial ultrasound studies and later came to necropsy were found to have periventricular leukomalacia (PVL). Thirteen were diagnosed in life and there was one false positive diagnosis giving an accuracy of 91%, sensitivity of 72% and specificity of 98%. In 11 infants with sequential studies, who died at ages from 43 h to 3 years, the ultrasound findings were correlated with those at postmortem to establish the natural history of the condition. In infants who died within 7 days following the onset of the ultrasound changes, postmortem revealed early PVL without cysts: there were small haemorrhages into the affected areas in three of the four cases. In the five infants who died between 10 days and 9 weeks, cystic lesions were identified in life and at postmortem, but in two long-term survivors cysts resolved on ultrasound at 3-4 months of age. Correlation of ultrasound with postmortem findings demonstrated that, although the ultrasound lesions resolve, glial scarring and impaired myelination can still be demonstrated on careful pathological examination.