Peritoneal dialysis (PD) is a well-established therapeutic option for patients with polycystic kidney disease. However, in patients with massive polycystic kidney and liver disease, subclinical hepatic venous outflow obstruction may elicit the appearance of ascites after implantation of a peritoneal catheter. The case of a patient who developed ascites after implantation of a PD catheter and further lowering of abdominal pressure after unilateral nephrectomy is discussed.