BACKGROUND Peritoneal dialysis (PD) is probably underused because of fears concerning the body image of patients. For the purposes of providing exact information for patients when choosing between PD and hemodialysis, we studied the extent of increase in waist circumference by infusing dialysate. METHODS The abdominal circumference of 44 PD patients was measured before and after infusion of dialysate. The change in circumference was compared to body mass index (BMI) and length of the abdominal cavity, defined by the distance between the processus xiphoideus and the os pubis. RESULTS Mean abdominal circumferences at the umbilicus and the iliac crest increased from 92.6 +/- 10.1 to 95.5 +/- 10.0 cm and from 95.2 +/- 8.5 to 96.2 +/- 6.3 cm, respectively, when dialysate was infused (p value for both < 0.01). A dialysate volume of 2000 mL increased the circumference only slightly more than the increase seen with 1500 mL. The change in circumference was not correlated with the circumference before the infusion, BMI, height of the patient, or length of the abdominal cavity. CONCLUSIONS This study shows that normal PD fill volumes increase the waist circumference only a little. This finding should ease the patient's presumption of PD changing the body image.