Background: Red blood cell distribution width (RDW) is recognized predictor for all cause mortality in patients on hemodialysis. In this study, we assessed whether RDW was associated with all-cause mortality in patients on peritoneal dialysis (PD). Methods: From January 2007 to January 2014, 58 patients were treated with PD at the Presbyterian medical center. Of these, we included 54 patients who had more than 1 year follow-up period, and performed a retrospective analysis of demographic, biochemical parameters, and patient outcomes. Following one-year, all-cause mortality was evaluated. Results: Of 54 patients, 5 patients died during the follow-up period of one-year. Patients with high RDW levels showed significantly higher 1-year mortality rates than patients with low RDW levels (p<0.01). In comparison with survivor, patients who died had significantly higher initial RDW levels (15.4±0.7% vs 13.8±1.6%, p=0.004) and lower serum albumin levels (3.3±0.5 vs 2.6±0.4, p=0.01). In multivariate logistic regression analysis, RDW and serum albumin at starting on PD were independent risk predictors for 1 year all-cause mortality. Conclusion: RDW could be an additive predictor for all-cause mortality in patients on peritoneal dialysis.