Cardiovascular disease is the leading cause of death in ESRD patients and is strongly associated with malnutrition. The mechanism of malnutrition is not clear, but hypermetabolism is suggested to contribute to cardiac cachexia. This study examined resting energy expenditure (REE) in relation to the clinical outcomes of ESRD patients who receive continuous ambulatory peritoneal dialysis (CAPD) treatment. A prospective observational cohort study was performed in 251 CAPD patients. REE was measured at study baseline using indirect calorimetry together with other clinical, nutritional, and dialysis parameters. Patients were followed up for a mean +/- SD duration of 28.7 +/- 14.3 mo. REE was 39.1 +/- 9.6 and 40.1 +/- 9.0 kcal/kg fat-free edema-free body mass per day for men and women, respectively (P = 0.391). Using multiple regression analysis, fat-free edema-free body mass-adjusted REE was negatively associated with residual GFR (P < 0.001) and serum albumin (P = 0.046) and positively associated with diabetes (P = 0.002), cardiovascular disease (P = 0.009), and C-reactive protein (P = 0.009). At 2 yr, the overall survival was 63.3, 73.6, and 95.9% (P < 0.0001), and cardiovascular event-free survival was 72.3, 84.6, and 97.2% (P = 0.0003), respectively, for patients in the upper, middle, and lower tertiles of REE. Adjusting for age, gender, diabetes, and cardiovascular disease, patients in the upper and middle tertiles showed a 4.19-fold (95% confidence interval, 2.15 to 8.16; P < 0.001) and a 2.90-fold (95% confidence interval, 1.49, 5.63; P = 0.002) respective increase in the risk of all-cause mortality compared with those in the lower tertile. However, the significance of REE in predicting mortality was gradually reduced when additional adjustment was made for C-reactive protein, serum albumin, and residual GFR in a stepwise manner. In conclusion, a higher REE is associated with increased mortality and cardiovascular death in CAPD patients and is partly related to its close correlations with residual kidney function, cardiovascular disease, inflammation, and malnutrition in these patients.