♦ Background: Peginesatide is a novel, synthetic, peptidebased pegylated erythropoiesis-stimulating agent that is designed specifically to stimulate the erythropoietin receptor. The purpose of the present study was to assess, for the first time, the efficacy and safety of peginesatide in chronic kidney disease (CKD) patients receiving peritoneal dialysis (PD) and previously on epoetin treatment. ♦ Methods: In this open-label multicenter study, 59 PD patients with CKD were converted from epoetin (alfa or beta) to once-monthly peginesatide. Doses were titrated to maintain hemoglobin levels between 10 g/dL and 12 g/dL during the 25 weeks of the study. The primary endpoint was change from baseline in mean hemoglobin values during the evaluation period (weeks 20 -25). ♦ Results: The mean hemoglobin value during the evaluation period was 11.3 ± 1.07 g/dL, and the mean change from baseline was 0.10 ± 1.15 g/dL (95% confidence limits: -0.24, 0.44 g/dL). During the evaluation period, most patients maintained hemoglobin levels between 10 g/dL and 12 g/dL (63.0%) and within ±1.0 g/dL of baseline (60.9%). The median weekly epoetin dose at baseline was 96.0 U/kg, and the median starting peginesatide dose was 0.047 mg/kg. Forty-three patients (72.9%) completed the study. Six patients (10.2%) received red blood cell transfusions. The observed adverse event profile was consistent with underlying conditions in the PD patient population. The most common adverse event was peritonitis (20.3%), a complication commonly associated with PD. Four deaths occurred during the study (2 related to septic shock, and 1 each to myocardial ischemia and myasthenia gravis). ♦ Conclusions: In this study, once-monthly peginesatide maintained hemoglobin levels in PD patients after conversion from epoetin.