Background: Apart from lipid-lowering drugs, dietary changes can also reduce plasma LDL-C concentrations. No studies have been conducted to investigate the clinical effects of a diet with traditional foods originating from the Nordic countries. Method: In a randomised, controlled parallel-group intervention study 88 mildly hypercholesterolemic men and women were randomized to either an ad libitum Nordic diet (ND) or a control diet (CD) for 6 weeks. All meals and foods were provided to the participants in the ND group. Primary outcome measure was LDL-cholesterol, and secondary outcomes were blood pressure, plasma insulin and glucose concentrations. The ND was a high-fibre diet rich in plant foods (fruit, berries, vegetables, root vegetables, whole grain cereals and legumes), vegetable fats (rapeseed oil and nuts) and fatty fish, low-fat milk products, but low in salt, added sugars, saturated fats and red meats. Result: 86 subjects completed the study. Distribution of carbohydrates, fat and protein (E%) in ND was 54, 27, 19, respectively. ND lowered plasma total cholesterol 0.98±0.75 mmol/l (-16%), LDL-C by 0.83±0.67 mmol/l (-21%), HDL-C 0.08±0.23 mmol/l (-5%), including reduced LDL/HDL ratio by -0.42±0.57 (-14%) (all p<0.01 versus controls). Insulin concentrations decreased by 0.51± 2.25 (-9%, p=0.01) and systolic blood pressure by 7±13 mmHg (-5%, P<0.01) compared to controls. Despite diets were eaten ad libitum, body weight decreased by 3.0 kg in the ND (P<0.001). No significant differences were found for diastolic blood pressure, triglycerides or plasma glucose. Conclusion: A Nordic diet improves blood lipid profile, and insulin sensitivity as well as lowering blood pressure to a clinically significant extent in hypercholesterolemic subjects.