A group of 13 patients on Continous Ambulatory Peritoneal Dialysis up to 18 months was studied. During the study period, Peritoneal Urea Clearance was stable. In all but 2 cases peritonitis did not depress the efficiency in clearing urea. When Peritoneal Urea Clearance was corrected for 1.73 m2 surface area, there was on the average an 11.8% increase over not corrected clearance rates. This increase was statistically significant.