• The effects of prednisolone were studied in 22 patients with neurological symptoms resulting from cerebral tumors. The primary lesion was mammary carcinoma in 15 cases and bronchogenic carcinoma in 2; in one patient each it was uterine carcinoma, malignant melanoma, and pancreatic carcinoma. Two patients had inoperable primary tumor of the brain: one acoustic neurinoma and one craniopharyngioma. The basic dose was 50 mg. of prednisolone twice daily by mouth, generally continued for three or four months. Remarkable temporary improvement in neurological symptoms was seen in 14 patients. This effect usually was not explained by any actual regression of the tumors or by any simple relation to the nature of the primary lesion. It seemed most likely that the relief afforded by prednisolone depends on its anti-inflammatory effect and that lesions surrounded by edema improve somewhat while those surrounded by hemorrhage are unaffected. The favorable effects lasted several weeks to several months, but in one patient still continue after 15 months of therapy.