This thesis is concerned with a study of the clinical and biological effects of recombinant human erythropoietin (EPO) which recently became available as a novel treatment for the anaemia of end-stage renal disease. The dissertation begins with an introductory chapter which contains a historical note and survey of the relevant published literature. In this section is included a review of the pathogenesis of renal anaemia, the traditional treatment options for this condition, the development of recombinant human EPO, the biochemistry and physiology of erythropoietin, the metabolic fate of EPO, and the early clinical trials with EPO. This is followed by seven chapters of original work undertaken in Cardiff between April 1988 and July 1990.