A 65-year-old woman with B-cell chronic lymphocytic leukemia (CLL) and pure red cell aplasia (PRCA) is described. After initial chemotherapy with three different regimens over 3 months (prednisone, chlorambucil/vincristine, cyclophosphamide, bleomycin/cyclophosphamide, etoposide, prednisone), normalization of the blood lymphocyte count was observed, but lymphocyte infiltration of the bone marrow persisted and erythropoiesis remained virtually absent. Monotherapy with cyclosporin-A (CyA) was begun. After 35 days, a marked increase in the reticulocyte count was observed, and with continuing therapy, there was a rapid increase in the hemoglobin level. Follow-up after 13 months of uninterrupted treatment with CyA revealed remission of both CLL and PRCA. CyA should be investigated further as a therapeutic modality for PRCA in patients with CLL, and such trials might provide further clues to the pathogenesis of this peculiar association.