In a multicenter analysis, the effect of low-dose cytosine arabinoside (Ara-C)(10 mg/ m2q 12 h subcutaneously for a minimum of 15 days) has been assessed in 13 patients with acute leukemia (10 myeloid-AML-, 3 lymphocytic-ALL-) and 7 patients with dysmyelopoietic syndromes (DMPS), conditions classified as refractory anemia with an excess of blasts ( RAEB ). Seven patients suffering from acute leukemia and 1 with DMPS in blastic transformation displayed a leukocytosis of more than 10 X 10(9)/1. Three out of 7 DMPS, 1 out of 10 AML achieved a complete remission, 1 out of 3 ALL-patients reached a partial remission twice. Seven patients showed a blast clearing in the bone marrow and peripheral blood, in another 7 instances examination of the bone marrow was not performed after therapy because of early death. The majority of patients were in their late phase of disease and refractory to conventional chemotherapy. Only 5 patients had no pretreatment at first presentation before low-dose Ara-C was initiated. At least for the DMPS-group, this therapeutic approach seems to be of some benefit.