The research programme is focussed on (1) various aspects of the peritoneum as a dialysis membrane for renal replacement therapy and (2) factors that determine the outcome of chronic dialysis patients. The first subject includes studies on peritoneal transport physiology, peritoneal effluent markers of the status of the membrane, morphological studies and investigations on determinants of peritoneal membrane alterations. These studies are done in peritoneal dialysis patients and in a chronic peritoneal exposure model in the rat. Determinants of outcome in chronic dialysis are investigated in the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD). This is a large multicenter prospective cohort study in incident haemo- and peritoneal dialysis patients. Specific items are analyses of effects of co-morbidity, time of dialysis institution, residual renal function, dialysis mode and dose and nutritional status. Besides mortality and morbidity outcome is also assessed as quality of life.