The effects of continuous flow left ventricular assist device (CF-LVAD) support on microvascular endothelial function in New York Heart Association (NYHA) class IV heart failure (HF) patients are currently unknown. Microvascular endothelial function was assessed by beat-to-beat plethysmographic measurement of finger arterial pulse wave signal changes for 5 min following reactive hyperemia. A group of seven NYHA class IV HF patients was evaluated before CF-LVAD placement (HF), and a second group of six NYHA class IV HF patients was evaluated 1-4 months following CF-LVAD placement (CF-LVAD). Additionally, a third group of seven age-matched healthy subjects served as controls (control). There was no significant (P > 0.05) difference among the three groups in age, weight, or height. Systolic blood pressure (BP) was significantly higher in the control group (120 ± 2 mmHg) as compared to that in the HF (97 ± 8 mmHg, P = 0.005) and CF-LVAD (106 ± 4 mmHg, P = 0.003) groups. Diastolic BP was significantly lower in the HF group (57 ± 5 mmHg) as compared to that in the control (71 ± 2 mmHg, P = 0.012) and CF-LVAD (80 ± 7 mmHg, P = 0.008) groups. The reactive hyperemic index (RHI), a measure of endothelial function, was significantly higher in the control group (2.373 ± 0.274) than in both the HF (1.543 ± 0.173, P = 0.013) and CF-LVAD (1.355 ± 0.163, P = 0.004) groups; however, there was no significant (P = 0.223) difference in RHI between the HF and CF-LVAD groups. The results of the present study demonstrate that while 1-4 months of CF-LVAD support do not negatively affect microvascular endothelial function, 1-4 months of CF-LVAD support do not significantly improve vascular function in resistance vessels.