Central nervous system involvement (CNS) of chronic lymphocytic leukemia (CLL) is a rare complication. Some analyses of autopsy studies suggest that the complication remains subclinical or is under-diagnosed. The symptoms of patients with leukemic CNS involvement are heterogeneous and nonspecific. Due to the low incidence, there are no treatment guidelines for this problem. Intrathecal chemotherapy and cranial irradiation are often performed.