A retrospective study of external lumbar subarachnoid drainage in 16 pediatric patients with severe head injuries is presented. All patients had Glasgow Coma Scale scores of 8 or lower at 6 hours postinjury and were initially treated with ventriculostomy. Five patients required surgical evacuation of focal mass lesions. All patients manifested high intracranial pressures (ICPs) refractory to aggressive therapy, including hyperventilation, furosemide, mannitol, and in some cases, artificially induced barbiturate coma. After lumbar drainage was instituted, 14 patients had an abrupt and lasting decrease in ICP, obviating the need for continued medical management of ICP. In no patient did transtentorial or cerebellar herniation occur as a result of lumbar drainage. It was also noted retrospectively that the patients in this study had discernible basilar cisterns on computerized tomography scans. Fourteen patients survived; eight made good recoveries, three are functional with disability, and three have severe disabilities. Two patients died, most likely from uncontrolled ICP before the lumbar drain was placed. It is concluded that controlled external lumbar subarachnoid drainage is a useful treatment for pediatric patients with severe head injury when aggressive medical therapy and ventricular cerebrospinal fluid evacuation have failed to control high ICP. Selected patients with elevated ICP, which may be a function of posttraumatic cerebrospinal fluid circulation disruption and/or white matter cerebral edema, can be treated with this modality, which accesses the cisternal spaces untapped by ventriculostomy.