Thirty-five patients with meningiomas were compared with 37 patients with astrocytomas with respect to the postoperative course of their ICP and elastance. In the case of the meningioma patients, the ICP increased on average over a longer period and achieved higher values than in the astrocytoma patients. In the first group, the elastance attained values that were three times as high as in the second group. There was no fixed relationship between pressure and elastance in the two groups of patients.