Using 31P-nuclear magnetic resonance (NMR) measurements of relaxation rate for 2,3 diphosphoglycerate (DPG) phosphorus atoms, we showed previously that in uraemic red blood cells the DPG-haemoglobin binding is stronger, thus stabilizing the deoxyhaemoglobin form and hence facilitating oxygen release. Here we verified if these modifications of spatial environment of DPG remain in uraemic patients treated by human recombinant erythropoietin (rHuEpo). Simultaneously we measured the intraerythrocytic ATP concentration (ATPi) and pH (pHi) of patients. Our results show a slight decrease on pHi and ATPi values during rHuEpo treatment. For the DPG relaxation rates, we observed a very weak but statistically significant increase 6 months after the beginning of treatment, but we cannot attribute a physiopathological significance to these results because of the lack of accuracy of the NMR determination of relaxation rate in red blood cells. Therefore, the DPG-haemoglobin binding is always stronger than in normal subjects.