Purpose: This study was done to identify the effects of self-care behavior, self-efficacy and family support on the occurrence of peritonitis in patients on CAPD (Continuous Ambulatory Peritoneal Dialysis). Methods: Data were collected from 81 patients on CAPD either as out-patients or in-patients between July and September 2004. Data were analyzed to identify relevant frequencies, percentages, averages, and standard deviations, and t-test and logistic regression were done using SPSS WIN 10.0 Results: a) Mean score for self-care behavior was 2.9 (of a possible 4.0), for general self-efficacy, 3.2 (of a possible 5.0), for specific self-efficacy 3.5 (of a possible 5), and for family support, 3.7 (of a possible 5). Family support generally showed the most positive results. b) Occurrence of peritonitis was not affected by general characteristics. c) There was a significant difference in the occurrence of peritonitis in terms of self-efficacy. Patients with peritonitis had lower self-efficacy than those who did not. 4) Of the four factors reviewed in relation to peritonitis, only self-efficacy was statistically significant: an increase in self- efficacy by 1 point increased the occurrence of peritonitis by 0.90. Conclusion: Among the four factors potentially affecting peritonitis in CAPD patients, general self-efficacy was found to be the main factor influencing the occurrence of peritonitis.