A 7-month-old boy with postnatal jaundice was operated upon at the age of 3 months for hypertrophic pyloric stenosis associated with water and electrolyte metabolism disturbances. During induction of anaesthesia cardiorespiratory arrest occurred. The child was resuscitated successfully. After the operation bilateral pneumonia developed. After 3 months of relatively good health signs of increased intracranial pressure developed with high-grade papilloedema. Ventriculography with subdurography demonstrated presence of an extensive subdural hygroma about 2 cm thick. One year after treatment the condition of the child and his development are completely satisfactory.