Previous reports have shown that N-terminal pro-brain natriuretic peptide (NT-Pro-BNP) is a predictive marker for mortality in both peritoneal dialysis (PD) and hemodialysis (HD) patients. The aim of the present study was to clarify whether NT-Pro-BNP reflects a specific status in PD patients. We analyzed 40 stable PD patients, allocating them to one of two groups (20 each) according to the median value of NT-Pro-BNP: group A below and group B above 5423 pg/mL. In group B as compared with group A, red blood cell (RBC) counts, hemoglobin, hematocrit, sodium, chlorine, albumin, and daily urinary volume were significantly lower, and cardiothoracic ratio (CTR) and daily ultrafiltration volume were significantly higher. Patients using icodextrin and diabetic patients showed significantly higher NT-Pro-BNP values. We observed significant correlations between NT-Pro-BNP and RBC count, hematocrit, hemoglobin, sodium, chlorine, albumin, lactate dehydrogenase, CTR, daily urinary volume, and ultrafiltration volume. Multiple regression analysis revealed that increasing CTR and hyponatremia were significant predictors of an increase in NT-Pro-BNP. Our results indicate that increased serum NT-Pro-BNP well reflects anemia status, water balance, hyponatremia, and hypoalbuminemia in prevalent PD patients.