Exchanges were performed in 1-hour and 3- to 5-hour cycles when patients were noninfected and during episodes of peritonitis. The hourly exchange dialysate effluent volume decreased with the occurrence of peritonitis. These exchanges were associated with increased glucose absorption from dialysate, diminished sodium removal and augmented clearances of urea and creatinine. Protein losses were increased in the dialysate effluent of patients during an episode of peritonitis during the hourly exchanges. In the long-dwell exchanges obtained after clinical improvement of peritonitis, only protein losses were increased over control. Clearances, sodium loss in dialysate and glucose absorption were not altered from control.