Background: Many patients prescribed cholesterol-reducing drugs do not achieve target cholesterol levels. Soy protein reduces plasma cholesterols in patients with untreated hypercholesterolaemia. Objective: To test whether Abacor®, a newly developed soy-based dietary supplement, further reduces plasma cholesterol concentrations when given to hypercholesterolaemic patients in statin treatment. Design: In total, 49 patients (m/f=34/15, age 43-79 years) completed the study. All had a plasma LDL cholesterol concentration >3.0 mmol/l at baseline despite statin treatment. Within the study, participants received statin monotherapy for 6 weeks, statin+Abacor® for 6 weeks and finally statin monotherapy for further 6 weeks. Results: The plasma concentrations of total cholesterol and of LDL cholesterol were significantly lower at visit 5 (6 weeks of combination treatment) than the mean value of the concentrations at visit 3 and visit 6 (both after 6 weeks of statin monotherapy), 5.5±0.1 vs. 5.9±0.1 mmol/l, p<0.0004 and 3.3±0.1 vs. 3.6±0.1 mmol/l, p<0.0006. Conclusion: The soy-based dietary supplement Abacor® has a total and LDL cholesterol reducing effect when given as supplement to statins in hypercholesterolaemic patients.