Refractory heart failure is a major cause of mortality and hospitalization, and peritoneal dialysis (PD) is one of the options for controlling volume overload. Although high glucose dialysate enables a large amount of ultrafiltration, the use of 4.25% glucose dialysate is generally avoided, because high glucose exposure leads to peritoneal damage. Here, we describe a patient who was successfully treated with assisted automated PD using 4.25% glucose dialysate for refractory heart failure. An 84-year-old woman developed heart failure due to severe mitral regurgitation with a low left-ventricular ejection fraction of 30%, and also developed progressive kidney deterioration. She had been refractory to diuretics and repeatedly hospitalized. PD was started to treat refractory heart failure. Since it was difficult for her to change the dialysis bags by herself, assistance with her PD from her family was needed. The use of 4.25% glucose dialysate markedly increased ultrafiltration and improved her condition. In addition, automated PD (APD) using 4.25% glucose dialysate enabled her family to have a break from PD once every 4 days. Thereafter, she had no episodes of hospitalization due to heart failure for approximately 18 months after her discharge.