Amifostine is a phosphorylated aminothiol that not only protects hematopoietic progenitor cells from chemotherapy and radiotherapy, but also stimulates normal hematopoiesis. The effect of amifostine on the in vitro growth of hematopoietic progenitors derived from B-cell chronic lymphocytic leukemia(B-CLL) was investigated. The colony-forming units (CFU)-granulocyte macrophage (CFU-GM), the burst-forming units-erythroid (BFU-E) and the CFU-granulocyte erythroid macrophage megakaryocytes (CFU-GEMM) increased 38, 20 and 100%, respectively, after the incubation with amifostine. There was no statistical difference in the in vitro progenitor growth of patients grouped according to their disease stage, bone marrow lymphocytic infiltration or therapy. Our data indicate that apart from cytoprotection the parallel use of amifostine and chemotherapy in patients with B-CLL could enhance bone marrow recovery.