An 18-yr-old female with chronic active hepatitis developed a severe anemia due to a lack of red cell production. Her bone marrow showed many large proerythroblasts but an almost complete lack of more mature erythroblasts. Incubation of the marrow cells in a normal medium with erythropoietin concentrate led to increased erythropoiesis as indicated by the development of mature erythroblasts as well as a ninefold increase in hemoglobin synthesis. The patient's plasma was cytotoxic for erythroblasts. Following splenectomy, a remission of the disease occurred. This study indicates that in some cases the anemia associated with abundant marrow proerythroblasts and the absence of mature erythroblasts has the same pathogenesis as pure red cell aplasia and that splenectomy may be beneficial when there is a lack of response to immunosuppressive drugs.