Objective: Because the lipoprotein effects of statin and fibric acid derivatives therapies differ, we studied the effects of these therapies in patients with hyperlipidemia on lipoproteins, vasomotor function, and plaque stability. Methods: We administered simvastatin, 20 mg daily, to 27 patients with hypercholesterolemia and coronary artery disease, or fenofibrate, 200 mg daily, to 27 patients with pure hypertriglyceridemia during 8 weeks. Results: As expected, simvastatin significantly lowered total cholesterol and low-density lipoprotein cholesterol (LDL-C) more, and fenofibrate decreased triglyceride and increased high-density lipoprotein cholesterol (HDL-C) more than either therapy. Simvastatin and fenofibrate significantly improved the percent flow-mediated dilator response to hyperemia, by 183 +/- 41% and by 30 +/- 7%.. respectively (each P < 0.001); however, simvastatin significantly improved more (P < 0.001). Simvastatin and fenofibrate significantly lowered plasma levels of tumor necrosis factor alpha (TNF-alpha) by 13 +/- 4% and by 10 +/- 4%, respectively (P = 0.009 and P = 0.006, respectively) with a similar degree (P = 0.614). Simvastatin significantly reduced plasma levels of total MMP-9 and TIMP-I more (P = 0.005 and P = 0.036,. respectively), compared with fenofibrate showing no reduction. There were significant correlations between the degree of changes in TNF-alpha and the degree of changes in MMP-9 activity (r = 0.376, P = 0.053). Conclusions: Simvastatin and fenofibrate demonstrated antiatherosclerotic effects via different mechanisms. (C) 2003 Elsevier Ireland Ltd. All rights reserved.