Neurotoxicity is a common and potential dose-limiting complication of cancer chemotherapy. For most agents, high-dose therapy, combination chemotherapy, concomitant cranial radiotherapy, and intracarotid or intrathecal injection are more likely to produce neurologic complications than standard oral or intravenous therapy. Any portion of the nervous system can be damaged. Encephalopathies (either focal or diffuse) are produced by BCNU, cisplatin, cytarabine, 5-fluorouracil, ifosfamide, L-aspariginase, methotrexate, procarbazine, corticosteroids, and some biological response modifiers (interferon, interleukin-2). Cerebellar syndromes may follow the administration of cytarabine, 5-fluorouracil, and procarbazine. Myelopathy may complicate intrathecal methotrexate, cytarabine, thiotepa, and accidental intrathecal vincristine or doxorubicin injection. Peripheral neuropathy occurs from cisplatin, vincristine, and, sometimes, cytarabine or procarbazine. Myopathy is a common complication of corticosteroids. Strokelike syndromes may occur with L-aspariginase, high-dose methotrexate, and intracarotid BCNU or cisplatin. Differentiating the neurologic complications of chemotherapy from other neurologic complications of cancer is often difficult. As cancer patients are treated more aggressively, receive more chemotherapy, and live longer, and as new chemotherapeutic agents are developed and existing agents are used more intensively or in novel ways, neurologic complications of cancer chemotherapy will become more common, serious, and complex. The recognition and treatment of chemotherapy-induced neurotoxicity will become a frequent and important clinical problem for most neurologists.