Treatment results of leptomeningeal metastasis are reported in 33 breast cancer patients. They were divided into three groups: group 1, 19 patients, received intraventricular methotrexate (MTX) with doses based on CSF MTX levels; group 2, 6 patients, received whole brain radiation followed by a course of MTX given by lumbar punctures; group 3, 8 patients, was not treated. Median survival in group 1 was 6 months; 25% survived 1 year or more. Median survival (1 to 2 months) in groups 2 and 3 was significantly shorter. Neurologic improvement was seen in an average time of 4 weeks in about 80% of group 1 patients. Two of group 2 patients improved at 3 weeks, and all group 3 patients deteriorated. Carcinomatosis caused death significantly less often in group 1 than in the other groups.