Background <p>The effects of dapagliflozin on patients with end-stage kidney disease (ESKD) and chronic heart failure (CHF) who are on peritoneal dialysis (PD) are not well understood. The jDAPA-PD is a proof-of-concept study designed to assess the efficacy and safety of dapagliflozin in such patients in Japan.</p> Methods <p>This is a multicenter, open-label, randomized controlled trial conducted on 40 patients with ESKD and CHF on maintenance PD, particularly those who have substantial residual kidney function. Patients who were recently on sodium–glucose cotransporter 2 inhibitors, hemodialysis, or treatment for peritonitis or those who have a daily urine volume of &lt; 500&#xa0;mL will be excluded from the study. Participants will be randomized&#xa0;in a 1:1 allocation to either 10&#xa0;mg dapagliflozin orally once-daily group or the standard treatment group. The change in extracellular water from baseline to week 24 is the primary endpoint, which will be measured by bioelectrical impedance analysis. The secondary endpoints are all-cause mortality, cardiovascular events, hospitalization, PD discontinuation, and changes in body composition, blood pressure, renal and cardiac function, brain natriuretic peptide, peritoneal function, PD regimen, and weekly fluid removal from baseline to week 24. The safety endpoints are adverse events and adverse drug reactions that occur during the study period.</p> Results <p>The first participant completed the treatment, and the study is now open for recruitment.</p> Conclusions <p>This study will determine whether the oral administration of 10&#xa0;mg of dapagliflozin for 24&#xa0;weeks is effective in fluid control for patients with CHF on PD. The study will also provide evidence of the safety data and multifaceted effects of dapagliflozin in patients on PD.</p> <p><i>Trial registration</i> jRCT1031230624 (registered on 5 February 2024).</p>