OBJECTIVES: We compared vascular and metabolic responses (and adverse responses) to statin and fibrate therapies alone or in combination in patients with combined hyperlipidemia. BACKGROUND: The mechanisms of action for statins and fibrates are distinct. METHODS: Fifty-six patients were given atorvastatin 10 mg and placebo, atorvastatin 10 mg and fenofibrate 200 mg, or fenofibrate 200 mg and placebo daily during each two-month treatment period of a randomized, double-blind, placebo-controlled crossover trial with two washout periods of two months‘ each. RESULTS: Lipoproteins were changed to a greater extent with combined therapy when compared with atorvastatin or fenofibrate alone. Flow-mediated dilator response to hyperemia and plasma high-sensitivity C-reactive protein and fibrinogen levels were changed to a greater extent with combined therapy when compared with atorvastatin or fenofibrate alone (p < 0.001, p = 0.182, and p = 0.015 by analysis of variance [ANOVA], respectively). The effects of combined therapy or fenofibrate alone on plasma adiponectin levels and insulin sensitivity (determined by the Quantitative Insulin-Sensitivity Check Index [QUICKI]) were significantly greater than those of atorvastatin alone (p = 0.022 for adiponectin and p = 0.049 for QUICKI by ANOVA). No patients were withdrawn from the study as the result of serious adverse effects. CONCLUSIONS: Combination therapy is safe and has beneficial additive effects on endothelial function in patients with combined hyperlipidemia.