One hundred and five children with malignant disease attended for lumbar puncture which was performed under general anaesthesia. A questionnaire was answered over the next three days to determine the incidence of post dural puncture headache Ninety-seven questionnaires were returned and the results show that no child aged under ten years developed a headache. Of the children aged 10-12 years, two out of seventeen developed a headache (11.8%). In children aged 13-18 years, five out of ten developed a headache (50%).