Clinicopathological evaluation of pineocytoma was performed in 4 patients. The subjects, 2 males and 2 females, ranged in age from 17 to 40. All the patients were clinically found to have the symptom of increased intracranial pressure on a monthly basis, but none of them were found to have dorsal midbrain dysfunction symptoms such as Parinaud's sign or Argyll Robertson pupil. Diagnostic imaging produced heterogeneous pictures indicating calcifications and cyst in 2 patients and homogeneous pictures of the tumor parenchyma in the other 2 patients. Histologically, the former cases were found to have many pineal-sand-like calcifications. Median sagittal MR images demonstrated expansive growth of pineocytoma. Quadrigeminal plates which kept their shapes were observed in 2 patients. Craniotomy was performed in all cases, removing the tumor totally in 2 patients. Radiation therapy was given to 3 patients, resulting in complete remission, but radiosensitivity varied according to cases. During the follow-up period of 12 to 42 months, one patient died of peritonitis caused by shunt infection. No recurrence of the tumor was seen in any of the patients. The incidence of pineocytoma was very low. Further evaluation of the tumor involving many cases is advisable.