Peritoneal clearances of urea (C(urea)) and creatinine (Ccr), peritoneal protein losses (PL) and ultrafiltration (UF) were retrospectively evaluated in 12 diabetic patients on continuous ambulatory peritoneal dialysis (CAPD) during a four year study. The average of three determinations each year was calculated. There were not significant differences in C(urea) (ml/24 hours), Ccr (ml/24 hours), PL (g/24 hours) and UF (ml/24 hours) between the four years and basal values or in the year to year studies. Seven patients did not modify their CAPD schedule during the four years study and we did not find any statistical differences in this group in the parameters studied. There was an average incidence of peritonitis of 4.7 episodes, higher in the 2 first years (p less than 0.05). The peritonitis incidence did not affect any of the functional parameters evaluated. The results of our study suggest that C(urea), Ccr, PL and UF in diabetic patients are not affected by long-term CAPD or by the peritonitis incidence.