© 2014 Elsevier Ltd. Background: Dyslipidemia is an established feature of metabolic syndrome (MS) that is associated with an increased risk of atherosclerotic cardiovascular disease. Curcuminoids are natural products with anti-atherosclerotic and lipid-modifying effects but their efficacy in patients with MS has not yet been tested. Objective: To investigate the effects of bioavailability-enhanced curcuminoids, as adjunctive to standard of care, on serum lipid concentrations in patients with MS. Methods: Patients diagnosed with MS according to the NCEP-ATPIII criteria who were receiving standard of care were assigned to either curcuminoids (C3 complex®; 1000mg/day; n=50) or placebo (n=50; matched with drug capsules in shape and color) for 8 weeks. In order to improve the oral bioavailability, curcuminoids were co-administered with piperine (bioperine®) in a ratio of 100:1. Serum concentrations of total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides, small dense LDL (sdLDL), lipoprotein(a) [Lp(a)], and non-HDL-C were determined at baseline and at the end of 8-week treatment period. Results: Curcuminoids were more effective than placebo in reducing serum LDL-C, non-HDL-C, total cholesterol, triglycerides and Lp(a), and elevating HDL-C concentrations. However, changes in serum sdLDL levels were found to be comparable between the study groups. The effects of curcuminoids on triglycerides, non-HDL-C, total cholesterol and Lp(a) remained significant after adjustment for baseline values of lipids and body mass index. Conclusion: Curcuminoids-piperine combination is an efficacious adjunctive therapy in patients with MS and can modify serum lipid concentrations beyond what is achieved with standard of care.