The aim of this study was to evaluate the correlations between microalbuminuria (MAU) and endothelial function in hypertensive patients with carotid plaques (CP). A total of 71 hypertensive patients with CP (CP group) and 20 healthy people as normal controls (NC group) were enrolled in this study. The CP group was divided into an MAU group (MAU group, n = 33) and a non-microalbuminuria group (NM group, n = 38) according to their urinary albumin excretion rates (UAER). Endothelial function was assessed by flow-mediated dilation (FMD) in the brachial artery by ultrasonography, and nitroglycerin-mediated dilation (NMD) was used as a control test for FMD. Intima-media thickness (IMT) and biochemical parameters were evaluated. The ΔFMD% was significantly lower in patients with and without MAU in the CP group compared to the NC group. All patients with MAU had significantly lower ΔFMD% and ΔNMD% compared to the patients without MAU. ΔFMD% showed significant negative correlations with IMT, systolic blood pressure, glucose, total cholesterol, low density lipoprotein, high-sensitivity C-reactive protein, and log UAER. ΔNMD% demonstrated significant negative correlations with age, IMT, systolic blood pressure, glucose, and log UAER. Stepwise multiple linear regression analysis revealed that FMD was independently correlated with UAER and total cholesterol, while NMD was independently correlated with UAER and age. These results suggest that MAU might aggravate the arterial dysfunction and play a role in the arterial endothelial function in patients with hypertension and CP. Both endothelium-dependent and endothelium-independent vasodilatations were impaired in hypertensive patients with CP.