Obtain initial estimates of the change in brachial artery endothelial function and maximal oxygen uptake (VO2peak ) with 8 weeks of low-frequency electrical muscle stimulation (LF-EMS) or sham in patients with advanced chronic heart failure. Using a double blind, randomized design, 35 patients with chronic heart failure (New York Heart Association class III-IV) were assigned to 8 weeks (5 × 60 min per week) of either LF-EMS (4 Hz, continuous) or sham (skin level stimulation only) of the quadriceps and hamstrings muscles. Four of the five sessions were at home and one under supervision. Ultrasound images of resting brachial artery diameter and post 5 min occlusion to determine flow-mediated dilation (FMD), a marker of vascular function and peak oxygen uptake (VO2peak ) during cardiopulmonary exercise test, were measured before and after LF-EMS (n = 20) and sham (n = 15) interventions. FMD improved by 2.56% (95% confidence interval: 0.69 to 3.80) with LF-EMS compared with sham (P = 0.07). There were no notable changes in VO2peak . Improvements in FMD with LF-EMS may have a clinically meaningful effect as higher FMD is associated with better prognosis. This is a preliminary finding, and a larger trial is warranted.