This paper summarizes results of rhuEPO--treatment obtained by different authors in 27 patients with a myelodysplastic syndrome (MDS). Only 1/3 of all patients with a MDS were responsive to rhuEPO treatment, while in 2/3 of these subjects no amelioration of anaemia was noticed, even after extremely high doses of this hormone. A detailed description of a patient with MDS, which was observed by the authors, is presented. In this patient the anaemia was refractive even after very high doses of rhuEPO administered for 10 weeks.