Two patients who had both B-cell chronic lymphocytic leukemia (CLL) and dyserythropoiesis are described. One patient (Case 2) had both CLL and dyserythropoiesis. Erythrodysplasia developed in the other patient (Case 1) after treatment for CLL with alkylating agents and 2'-deoxycoformycin. The management of these patients and the possible mechanisms responsible for the development of dyserythropoiesis in CLL are discussed.