Chronic Kidney Disease (CKD) patients are at increased risk of cardiovascular disease. Endothelial dysfunction, characterized by a reduced bioavailability in nitric oxide, is an independent predictor of cardiovascular disease in CKD. Increased oxidative stress is a potential cause of endothelial dysfunction in this patient cohort. This study investigates the role that mitochondrial derived oxidative stress plays in CKD related vascular dysfunction. In a controlled, double blinded trial, Stage 3-5 CKD patients will be randomly assigned to receive a 4 week daily dose of a mitochondria targeted antioxidant (MitoQ) or a placebo.