In neonates pontosubicular necrosis (PSN) is one of the patterns of acute brain injury, the sites of maximum damage being the basis pontis and the subiculum of the hippocampus. A retrospective clinical and pathological study was performed on 16 preterm and 2 term neonates with PSN and compared with 16 age-matched controls. The results indicated that hypocarbia of less than 20 mmHg was one of the important factors in the pathogenesis of PSN.