© 2017 by The Medical Bulletin of University of Health Sciences Haseki Training and Research Hospital The Medical Bulletin of Haseki published by Galenos Yayınevi.Aim: Asymmetric dimethylarginine (ADMA) is associated with increased coronary artery disease risk through endothelial dysfunction in dialysis patients. We aimed to investigate the role of flow-mediated dilatation (FMD), a non-invasive indicator of endothelial function, and ADMA in mortality in peritoneal dialysis (PD) patients. Methods: PD patients aged 18-80 years; with dialysis duration of at least three months were included. FMD measurement and ADMA levels were recorded. Outcome of the patients on the third year were analyzed with binary logistic analyses. Results: The mean age of the 55 patients was 53±15 years and the mean follow-up duration was 36 months. Mean FMD and ADMA levels were 10.6±6.4% and 81.8±48.0 mol/L, respectively. Eighteen patients died during follow-up. Age, presence of diabetes mellitus and ischemic heart disease, ultrafiltration amount and serum albumin level were related with mortality while gender, weekly Kt/V and ADMA levels were not. There was no significant relationship between ADMA level and FMD (p=0.873). FMD was negatively correlated with systolic and diastolic blood pressures (p=0.001, p<0.001, respectively). Hypertension was found to be the most important single factor determining FMD (p=0.037). Conclusion: Estimating endothelial function by FMD or measuring serum ADMA levels may not be useful for predicting mortality in PD patients.