This report describes our experience with the use of osmotic diuretics, governed by continuous monitoring of intracranial pressure (ICP), as the primary treatment for 12 consecutive patients suffering from an acute, supratentorial intracerebral hematoma. In all cases the hematoma, as shown by computed tomographic scan, had a long axis of greater than 4.0 cm. ICP and cerebral perfusion pressure were successfully maintained within the assigned limits in all patients, and in none was surgical evacuation required. There was one death during the 6-month follow-up period. With appropriate weighting to differences in admission status, statistical comparison of the patient outcome in the present series with that reported by McKissock et al. suggests that ICP monitoring can improve the outcome of conservatively (and perhaps surgically) treated patients.