A survey of the literature suggests continued interest in modifying the composition of peritoneal dialysis solutions. Osmotic agents such as glucose polymers and short-chain polypeptides may find a role in peritoneal dialysis fluids as partial substitutes for dextrose. New solutions containing amino acids should serve as more than sinks for uremic toxins by providing nutritional support and by ameliorating uremic lipid abnormalities. Increasing emphasis is being paid to biocompatibility during the development of new peritoneal dialysis fluids.