The clinical aspects of peritonitis were reviewed in 83 patients treated with continuous ambulatory or continuous cyclic peritoneal dialysis between May 1978 and April 1988. Peritonitis occurred in 50 patients whose mean duration of dialysis was 17.8 months, but not in 33 patients with a mean duration of dialysis of 10.4 months. The mean time from starting dialysis to the first episode of peritonitis was 7.1 months. The peritonitis rate was lower for continuous cyclic than for continuous ambulatory peritoneal dialysis (1 episode per 12.9 vs. 1 episode per 8.1 patient months, respectively). In 39% of the episodes, gram stain of the dialysate was positive. The dialysate leukocyte count was higher in gram-negative than in gram-positive peritonitis. Seventy percent of the peritonitis episodes were gram positive, and Staphylococcus aureus was predominant. Only 1 of the 7 diapered infants had gram-negative organisms associated with peritonitis. Catheters were replaced in 48 cases, 26 because of infection. Sixty-nine percent of the patients were cured with antibiotic therapy alone. Although peritonitis was associated with a mortality rate of 1.2%, peritoneal dialysis remains the favored dialytic mode for children.