Efficacy and tolerability of artichoke dry extract (drug/extract ratio 25-35:1, aquous extract, CY450) as coated tablets containing 450 mg extract (tradename: Valverde Artischocke bei Verdauungsbeschwerden) was investigated in the treatment of hyperlipoproteinemia and compared with placebo. 143 adult patients with initial total cholesterol of > 7.3 mmol/l (> 280 mg/dl) were included in a double blind, randomized, placebo controlled, multi-center clinical trial. Patients received 1,800 mg artichoke dry extract per day or placebo over 6 weeks. Changes of total cholesterol and LDL-cholesterol from baseline to the end of treatment showed a statistically significant superiority (p = 0.0001) of artichoke dry extract over placebo. The decrease of total cholesterol in the CY450 group was 18.5% compared to 8.6% in the placebo group. LDL-cholesterol decrease in the CY450 group was 22.9% and 6.3% for placebo. LDL/HDL ratio showed a decrease of 20.2% in the CY450 group and 7.2% in the placebo group. There were no drug related adverse events during this study indicating an excellent tolerability of artichoke dry extract. This prospective study could contribute clear evidence to recommend artichoke dry extract CY450 for treating hyperlipoproteinemia and, thus, prevention of atherosclerosis and coronary heart disease.