Endothelial dysfunction is implicated in increased cardiovascular risk in nondialyzed population. However, the prognostic impact of endothelial dysfunction on cardiovascular outcome has not been investigated in peritoneal dialysis (PD) patients. We prospectively determined endothelial function by brachial artery endothelium-dependent vasodilation (flow-mediated dilation [FMD]) in 143 nondiabetic PD patients and 32 controls. Primary outcome was a major adverse cardiac and cerebrovascular event (MACCE). Brachial FMD was significantly lower in PD patients than in controls (2.9% [1.3-4.7] vs 6.2% [5.4-8.3], P < 0.001). During a mean follow-up of 42 months, primary outcome was observed in 25 patients (17.5%). When patients were dichotomized by the median value of FMD (2.9%), incidence rates of MACCEs were significantly higher in the group with lower FMD compared with higher FMD (7.2 vs 3.0/100 person-years, P = 0.03). In multivariate Cox analysis, low FMD (≤2.9%) was a significant independent predictor of MACCEs (hazard ratio = 2.73, 95% confidence interval = 1.03-7.22, P = 0.04). Furthermore, multivariate fractional polynomial analysis showed that the risk of MACCE decreased steadily with higher FMD values. Impaired brachial FMD was a significant independent predictor of MACCEs in PD patients. Estimating endothelial dysfunction by brachial FMD could be useful for stratifying cardiovascular risk in these patients.