Chronic kidney disease (CKD) affects more than 10~15% of the world's population and is steadily growing as a global health concern. Peritoneal dialysis (PD) contains the sequential peritoneal fluid exchange. The medical advantages of PD include the absence of the need for vascular access, preservation of residual renal function, and relatively lower cardiovascular stress due to continuous removal of extracellular fluid. Automated PD (APD), performed with a cycler device, makes PD a more convenient option.  I will present the principles of prescription for APD, including a brief review of peritoneal physiology and clinical issues for APD, such as residual renal function, fluid overload, and nutritional problems.