Hemorrhage from brain tumor was confirmed clinically, surgically, or on autopsy in 94 of 1861 cases (5.1%) treated during the past 18 years: 49 of 311 pituitary adenomas (15.8%) and 45 of 1550 other brain tumors (2.9%). The higher incidence of hemorrhage from pituitary adenoma was statistically significant (p less than 0.001). In brain tumors other than pituitary adenoma, the incidence of hemorrhage was significantly higher in the patients under 14 years old (17 of the 322 cases, 5.3%) than in the patients over 15 years old (28 of the 1228 cases; 2.3%) (p less than 0.001). Nineteen patients showed no evidence of clinical symptoms related to bleeding. Twenty-six patients had a definite history of an acute episode that suggested sudden bleeding. In 11 of these, the apoplectic syndrome was the initial presenting symptoms. The incidence of hemorrhage was not statistically correlated with sex. The hemorrhage was intratumoral in 30 cases, intracerebral in 7, subarachnoid in 7, and subdural in 1. The tumors were supratentorial in 36 cases, pineal in 1, and infratentorial in 8. Primary and metastatic choriocarcinoma and primary embryonal carcinoma seemed to cause hemorrhage most frequently. The following precipitating factors were found in 7 of the 17 patients aged under 14: ventricular drainage in 2, ventriculoperitoneal shunt in 2, carotid angiography in 1, head injury in 1, and leukemia in 1. Seven of the 17 patients under 14 years old died of massive bleeding from the tumor. Unless there is evidence of vascular disease such as cerebral aneurysm, vascular malformation, or hypertensive cerebrovascular disease, intracranial hemorrhage should be suspected of being due to a brain tumor.