Abstract: A peritoneal dialysis solution and method of administering same to a patient are provided wherein the sodium concentration in the solution is decreased thus causing sodium to be transported from the circulation to the peritoneal cavity. This provides for an improved ultrafiltration profile (more volume over a longer period of time) for the same initial osmolality when compared to standard solutions. Also, the same ultrafiltration profile as standard solutions can be achieved with lower initial osmolalities. A reduced amount of osmotic agent can be used to achieve equivalent ultrafiltration.