Intracranial pressure (ICP) was monitored in 9 patients with coma due to Reye-Johnson syndrome. Clinically unrecognized elevations of ICP were found in all patients and treated with ventricular fluid drainage and conventional osmotherapy. This adequately controlled ICP in 2 patients. Intractable intracranial hypertension in 4 patients responded to continuous intravenous glycerol infusion, 1 g/kg every 2 hours, administered as a 10 g/100 ml solution modified to substitute for maintenance fluids. Two patients required the addition of moderate hypothermia (30–32° C) to other therapeutic measures. Three patients survived, one with severe neurological sequelae. Before monitoring, 3 patients were suspected of herniation on clinical grounds (before they were monitored) and subsequently died. ICP monitoring with the goal of titrated control of ICP elevations could have been added to their supportive therapy at an earlier stage, possibly with the onset of coma and grade 3 EEG changes.