Acquired amegakaryocytic thrombocytopenia and pure red cell aplasia rarely occur concurrently. We report a case in which these disorders were associated with an occult large granular lymphocyte leukemia. The peripheral blood cytopenias improved after glucocorticoids and intravenous immunoglobulin were administered, and response was maintained with cyclosporine. Large granular lymphocyte leukemia should be suspected in the setting of unexplained bone marrow failure.