Leukemic and lymphomatous meningitis is a major presentation of primary or secondary central nervous system (CNS) involvement by aggressive lymphomas or acute leukemia. The medical literature and ongoing clinical trials were reviewed on the clinical presentation, diagnosis, prognosis, prevention, and treatment of leukemic and lymphomatous meningitis. Treatment for secondary leukemic and lymphomatous meningitis remains unsatisfactory, and efforts should be made to prevent and treat subclinical disease. Intrathecal and systemic chemotherapy remain the main therapeutic approaches for this disease. Outcomes have improved in patients with primary CNS lymphoma and meningeal involvement. Appropriate selection of patients at high risk for leukemic and lymphomatous meningitis is important so that preventive strategies can decrease the incidence of this complication of leukemia and lymphoma. Use of chemotherapy agents that cross the blood-brain barrier and the adoption of high-dose chemotherapy with autologous hematopoietic stem cell transplantation have increased the proportion of patients whose primary disease is cured.