We analyzed the frequency with which certain bacteria caused uncomplicated peritonitis in an adult continuous ambulatory peritoneal dialysis (CAPD) program that continued patients on this modality of therapy despite frequent infections. All infections were treated with a commonly employed 10- to 14-day course of narrow spectrum intraperitoneal antibiotics. Although the distribution of bacterial pathogens was similar to previous reports (coagulase-negative staphylococci, 43%; Staphylococcus aureus, 13%), we observed no episodes of fungal peritonitis. Twenty percent of our infections were associated with either "no specimens obtained" or "no growth," a finding similar to the CAPD registry. When the data were available, two thirds of all infections were caused by the same pathogen (genus and species) as in the most immediately preceding infection. Twenty-two of 96 episodes of uncomplicated peritonitis occurred within three weeks of a preceding infection. In all 11 cases where organisms were isolated from both paired episodes, the infecting agent was the same as in the preceding infection and was a staphylococcus. This high rate of apparent relapse and the absence of fungal infections may relate to our treatment protocol and possible explanations are discussed. Lastly, the occurrence of coagulase-negative staphylococcal peritonitis is a harbinger of future episodes of peritonitis caused by a variety of organisms.