End-stage renal disease patients receive peritoneal dialysis as a renal replacement therapy. The dialysis index must be regularly evaluated to achieve the target of adequacy. The definition of adequacy of peritoneal dialysis includes residual renal function, creatinine and urea clearance, fluid balance, nutrition and calcium, and phosphorus balance. Through this case discussion, we demonstrate the importance of "adequacy" and how to adjust dialysate regimen to achieve the goals of peritoneal dialysis.