The records of thirty-four patients with meningeal carcinomatosis treated at our hospital between 1984 and 1990 were reviewed. The sources, histologies, metastatic lesions outside the central nervous system, the history of the treatment of primary lesions and intraparenchymal of metastatic brain tumors and the period from the diagnosis of primary lesions and the treatment of intraparenchymal metastatic brain tumors to the diagnosis of meningeal carcinomatosis were investigated. Meningeal carcinomatosis was diagnosed and by neurological signs, CSF cytology, CT scan and MRI. Each patient was given a 5 mg single dose of methotrexate (MTX) alone or combined with 20 mg cytosine arabinoside (Ara-C) administered by intrathecal injection via an Ommaya reservoir and standard lumbar puncture with or without radiotherapy. Following intrathecal chemotherapy 22 of 29 patients showed symptomatic improvement of meningeal irritation and in 10 of 29 patients with cranial nerve impairment amelioration of symptoms was also observed. Moreover, CSF cytology became negative in 10 of 29 patients after a full course of intrathecal chemotherapy. Neurotoxicity Leukoencephalopathy, a neurotoxic effect of intrathecal chemotherapy was not observed in any of the patients. From these results, MTX in small doses is recommended for intrathecal chemotherapy of meningeal carcinomatosis to prevent neurotoxicity.