To test the hypothesis that cranial ultrasound correlated with post-mortem findings in neonates with hypoxic ischaemic encephalopathy (HIE), the brains of 20 infants who died after at least two real time ultrasound scans were examined. The ultrasound abnormalities detected in the periventricular/subcortical white matter, cortex or thalami were compared with the macroscopic and histological appearances. Comparing the last ultrasound scan which was performed no longer than 12 hours before the infant died, with histological data, the sensitivity and specificity for lesions in the thalamus was 100% and 83.3% respectively; for cortical lesions 76.9 and 100% respectively and for lesions in the periventricular white matter 80% and 75% respectively. The value of cranial ultrasound for detecting intracranial abnormalities in infants with HIE was considerably better than reported previously. This could mainly be attributed to the use of a 10 MHz transducer which was of critical importance to identify lesions in the superficial cortical layer.