There are conflicting data about the effects of cisplatin on erythropoietin (EPO) response to anemia. Aim of our study was to investigate whether endogenous EPO response to anemia in cisplatin treated patients was insufficient in comparison to the anemic chemotherapy-naive cancer patients and non cancer patients with iron deficiency anemia. Patients who had hemoglobin (Hb) levels of less than 110 g/l were included in the study. Fifteen chemotherapy-naive cancer patients were enrolled in Group A. Group B consisted of 15 patients who had been treated with three cycles of cisplatin chemotherapy and then became anemic and in Group C were included 15 patients who had iron deficiency anemia, without any malignancy. The mean Hb values were not different between all groups (102.8 +/- 39.8 g/l, 103.1 +/- 2.5 g/l and 99.3 +/- 3.6 g/l in Group A, Group B and Group C, respectively). However, EPO levels were found to be significantly lower in Group A and Group B than Group C (29.63 +/- 9.09 mU/ml, 20.87 +/- 2.43 mU/ml and 85.38 +/- 25.72 mU/ml, respectively; p=0.017 Group A vs. Group C, p=0.005 Group B vs. Group C). No significant difference was found between Group A and B (p=0.917).