Background and objectives: The impact of supervised exercise training on endothelial function in patients with intermittent claudication is unclear. This study assesses the impact of treadmill-based supervised exercise training alone or in combination with resistance training on pain free walking distance, flow-mediated dilatation, reactive hyperaemia index, nitric oxide and asymmetric dimethylarginine. Methods: Thirty-five patients with intermittent claudication were randomised to 12 weeks of treadmill-only supervised exercise training (Group 1) or a combination of treadmill and lower-limb resistance supervised exercise training (Group 2). Pain free walking distance was assessed by six-minute walk test. Endothelial function was assessed by brachial artery flow-mediated dilatation, reactive hyperaemia index and serum analysis of asymmetric dimethylarginine and nitric oxide. Results: Pain free walking distance improved within Group 1 (160 m to 204 m, p = 0.03) but not Group 2 (181 m to 188 m, p = 0.82), no between group difference. No significant change in flow-mediated dilatation or reactive hyperaemia index in either group. Nitric oxide decreased in Group 1 (15.0 µmol/L to 8.3 µmol/L, p = 0.003) but not Group 2 (11.2 µmol/L to 9.1 µmol/L, p = 0.14), p = 0.07 between groups. Asymmetric dimethylarginine decreased in Group 2 (0.61 µmol/L to 0.56 µmol/L, p = 0.03) but not Group 1 (0.58 µmol/l to 0.58 µmol/L, p = 0.776), no between group difference. Conclusion: Supervised exercise training does not improve endothelial function as measured by flow-mediated dilatation, reactive hyperaemia index and nitric oxide bioavailability.