Peritoneal dialysis is based on a simple technique but it is of great value in renal insufficiency or failure, especially in Pakistan where haemodialysis is not commonly available. Fundamentally, the technique consists in using the peritoneal membrance to filter the blood waste products by means of an osmotic gradient from the peritoneal vascular capillaries to the introduced fluid, which is then washed out. The fluid composition is similar to that of the normal extracellular fluid and as regards electrolytes much reduced amount of potassium and calcium lactate in place of bicarbonate is used but there are no organic constituents like proteins etc.