We reviewed our 115-month experience with continuous ambulatory peritoneal dialysis (CAPD) and continuous cycling peritoneal dialysis (CCPD) in adult and pediatric patients to determine whether there is a difference in the incidence of peritonitis between patients performing CAPD or CCPD. Peritonitis rates were similar in patients performing CAPD or CCPD in both the adult and pediatric age groups. The overall CAPD peritonitis rate was significantly lower in adult patients when compared with pediatric patients. There was no difference in peritonitis rates for CCPD between adult and pediatric patients. When the data are divided into 3-year subgroups, the incidence of peritonitis is significantly lower in adult patients undergoing either CAPD or CCPD when compared with pediatric patients during the years 1986 to 1988. There is significant improvement over time in the incidence of peritonitis in both adult and pediatric patients performing CCPD; similarly, there is a trend toward improvement in patients performing CAPD. Staphylococcus species organisms remain the most common bacterial cause of peritonitis, except in pediatric patients under the age of 2 years or with nephrostomies, where gram-negative rod infections were more common. Peritonitis resulted in discontinuation of peritoneal dialysis in a greater number of adult patients. These results suggest that the number of catheter manipulations is not important in determining the incidence of peritonitis. Pediatric patients are more likely than adult patients to develop peritonitis with either CAPD or CCPD. Adult patients are more likely than pediatric patients to discontinue peritoneal dialysis secondary to peritonitis.