Aim: The aim of our study was to investigate whether treatment with red yeast rice added with Coenzyme Q10 is associated with changes in endothelial function and arterial stiffness. Methods: This double blind, placebo-controlled, randomized clinical trial was carried out on 40 non-smoker moderately hypercholesterolemic subjects (ClinicalTrial.gov ID NCT02492464). After 4 weeks of diet and physical activity, patients were allocated to treatment with placebo or with an active product containing 10 mg monacolins and 30 mg Coenzyme Q10, to be assumed for 6 months. Endothelial reactivity and arterial stiffness have been measured through the validated Vicorder® device. Results: During monacolin treatment, patients experienced a more favorable percentage change in low density lipoprotein (LDL)-cholesterol (after monacolin treatment: -26.3%; after placebo treatment: +3.4%, p < 0.05). Endothelial reactivity (pulse volume displacement after monacolin treatment: +6.0%; after placebo treatment: -0.3%, p < 0.05), and arterial stiffness (pulse wave velocity (PWV) after monacolin treatment: -4.7%; after placebo: +1.1%, p < 0.05) also significantly improved only after monacolin treatment. Conclusion: The long-term assumption of the tested dietary supplement is associated with an improvement in LDL-cholesterolemia, endothelial reactivity and PWV in moderately hypercholesterolemic subjects.