Xuezhikang is a new blood-lipid-regulating medicine. The components of Xuezhikang include HMG-CoA reductase inhibitor (lovastatin), unsaturated fatty acids and many kinds of amino acids. A comparative study on the effects of Xuezhikang and Simvastatin (Zocor) was carried out. One hundred and eight patients with primary hyperlipidemia were randomly divided into two groups. Group 1 consisted of 53 patients, each taking 4 Xuezhikang capsules/day (1.2 g/day) for 8 weeks and group 2 included 55 cases, each taking Zocor 10 mg/day for 8 weeks. At the end of 8 weeks, the lipid levels were compared with those of the baseline in each group. In group 1 serum levels of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and triglycerides (TG) were decreased by 23.0%, 28.0% and 28.1% (P < 0.001) respectively and in group 2 they were reduced by 23.3%, 29.5% and 29.5% (P < 0.001) respectively. Serum level of high density lipoprotein (HDL-C) was increased by 5.0% (P > 0.05) with Xuezhikang and 14.3% (P < 0.01) with Zocor, but no significant differences were found between the two groups in TC, LDL-C, TG and HDL-C. The side effects of Xuezhikang were less than those of Zocor. It is suggested that Xuezhikang made in China is a safe, effective and tolerable lipid modulator.