BACKGROUND: Hypercholesterolaemia is a risk factor for coronary heart disease (CHD). Rosuvastatin is an HMG-CoA reductase inhibitor which has shown significantly greater lipid-lowering effects than all previously marketed statins. Omega-3 fatty acids (FA) from fish oil protect against coronary disease, mainly through antiarrhythmic and antiplatelet effects. Omega-3 FA also have lipid-modifying effects, mostly relating to triglyceride (TG) reduction. Thus, potential benefits could be expected from combined therapy with omega-3 FA and rosuvastatin OBJECTIVE: To investigate whether combined therapy with Omacor, a concentrate of omega-3, long chain, polyunsaturated fatty acids from fish oil plus Rosuvastatin offers benefits compared with rosuvasatin monotherapy with respect to the lipid profile of patients with type II hypercholesterolaemia. PATIENTS AND METHODS: This 8-weeks, randomized, single-blind, controlled trial was conducted at the Kwangju Christian hospital, Kwangju, Korea. Patients aged 50 to 70 years with type II hypercholesterolaemia were randomly assigned to receive combination therapy with rosuvastatin 10 mg/day plus Omacor 4g/day or monotherapy with rosuvastatin 10 mg/day. An interim and final check-up were performed at 4 and 8 weeks, respectively, after treatment was initiated. Physical signs and laboratory markers were assessed at baseline and after 4 and 8 weeks on therapy. RESULTS: A total of 43 patients (12 men, 31 women; mean [SD] age, 60 [5] years) were enrolled. After 8 weeks, lipid variables showed significant improvements over baseline in both groups (all, P < 0.05). Significant changes in LDL-C, HDL-C, and TG were found in the combination-therapy group (-30%, +28%, -27%, respectively) versus the monotherapy group (-24%, +16%, -16%, respectively; all, P < 0.05 between groups). Both treatments were well tolerated, with no significant differences in the incidences of adverse events. CONCLUSION: In this selected sample of patients with type II hypercholesterolaemia, the combination of Rosuvastatin plus omega-3 FA was associated with a more improved lipid profile than Rosuvastatin monotherapy, and was a well-tolerated and cost-effective therapeutic choice to treat these patients.