Pure red cell aplasia (PRCA) is a rare disorder, which is characterized by severe anaemia associated with reticulocytopenia and absence of erythroid precursor cell from the bone marrow. Mostly immunological mechanisms have a role in its pathogenesis. Primarily the acquired, idiopathic type occurs in adults, however, it is rarely associated with other disorders (autoimmune-, and lymphoproliferative diseases, etc.). The authors present a patient with B-cell chronic lymphocytic leukemia associated with PRCA, which was successfully treated with cyclosporine. The pathogenesis and the therapy of the PRCA is also summarized.