In order to reduce anaemia in patients with myelodysplastic syndromes (MDS) a stepwise treatment protocol including erythropoietin (EP) and granulocyte-macrophage colony-stimulating factor (GM-CSF) was designed. Thirty-seven MDS patients (stages I-III) with symptomatic anaemia were first given EPO 10,000 U s.c. 3 times weekly for 6 weeks. Those not responding, i.e. increased their haemoglobin levels > 15 g/l, proceeded into the second phase of the study where GM-CSF (200 micrograms/d. s.c. on weeks 1-6) was combined with EPO (10,000 U s.c. 3 times weekly on weeks 5-14). Following the initial EPO treatment phase, 14 of the 37 patients (38%) responded with increased haemoglobin levels. Responders were significantly different from non-responders in that their pre-treatment values of s-EPO, s-LDH and bone marrow blast cell counts were lower, their baseline haemoglobin levels higher and their transfusion dependency less pronounced. Eighteen of the 23 non-responders proceeded into the second phase, 13 of those were evaluable having completed the entire schedule. Three of the 13 initially EPO resistant patients (23%) responded to the GM-CSF/EPO combination with increased haemoglobin levels, suggesting a positive synergy between the two cytokines. Thus, the overall response rate to the present protocol was 46% (17 of 37 cases), but only a limited subset of the patients did clearly benefit from the combined GM-CSF/EPO administration. Therefore, we believe this step-wise approach to multiple growth factor treatment in MDS, starting with EPO alone and reserving the combination for refractory cases, has considerable advantages, taking into account both medical and socio-economical aspects.