Aims: A small body size may increase the risk for hernia development in patients on continuous ambulatory peritoneal dialysis (CAPD). The present study investigates whether there is a relationship between body size and hernia development in CAPD patients. Material and methods: The records of 78 patients on CAPD were reviewed retrospectively. Body mass index (BMI), body surface area (BSA) and total body water (TBW) were calculated in all patients. Correlations between different body size indicators (BMI, BSA and TBW) and hernia development were assessed using analysis of covariance in which we adjusted for sex. Results: A total of 14 patients (17.9%) with no physical evidence of hernia before catheter insertion developed hernias. Body size was significantly lower in CAPD patients with hernias than those without hernias when adjusted for sex. Conclusions: We conclude that patients with small body size tend to have an increased risk for hernia development. A simple estimation of patients' height, weight, body surface area and total body water would be helpful to predict development of hernias or other complications related to increased intraperitoneal pressure in CAPD patients.