OBJECTIVE: Subjects with the metabolic syndrome have reduced HDL cholesterol concentration and altered metabolism of high-density lipoprotein (Lp)A-I and LpA-I:A-II particles. In the metabolic syndrome, fenofibrate and atorvastatin may have differential effects on HDL particle kinetics. RESEARCH DESIGN AND METHODS: Eleven men with metabolic syndrome were studied in a randomized, double-blind, crossover trial of 5-week intervention periods with placebo, fenofibrate (200 mg/day), and atorvastatin (40 mg/day). LpA-I and LpA-I:A-II kinetics were examined using stable isotopic techniques and compartmental modeling. RESULTS: Compared with placebo, fenofibrate significantly increased the production of both LpA-I:A-II (30% increase; P < 0.001) and apoA-II (43% increase; P < 0.001), accounting for significant increases of their corresponding plasma concentrations (10 and 23% increases, respectively), but it did not alter LpA-I kinetics or concentration. Atorvastatin did not significantly alter HDL concentration or the kinetics of HDL particles. CONCLUSIONS: In the metabolic syndrome, fenofibrate, but not atorvastatin, influences HDL metabolism by increasing the transport of LpA-I:A-II particles