A 68-year-old man was diagnosed with chronic lymphocytic leukemia (CLL) 3 years ago. His course was progressive, and he was complicated with autoimmune hemolytic anemia (AIHA). After the lack of efficacy of prednisone and cyclo-phosphamide, rituximab (375mg/m(2)) was administered based on the presence of CD20 positive leukemic cells by flow cytometric analysis of bone marrow. During 4 courses of rituximab administration, both anemia and hemolysis improved dramatically. Furthermore, the percentage of CLL cells in his peripheral blood was reduced. Rituximab may be one of the effective treatments for CLL associated AIHA in Japan as well as in foreign countries.