Hypercholesterolemia is one of the major risk factors for atherosclerosis. Reduction of serum total and low density lipoprotein cholesterol(LDL-C) and the increase of high density lipoprotein cholesterol(HDL-C) are known to be associated with significant decrease of the incidence of atherosclerotic disease. HMG CoA reductase is known as rate limiting enzyme in the synthesis of cholesterol. Among many inhibitors of this enzyme pravastatin was recently released. To evaluate the efficacy and safety of this drug in Korean patients with hypercholesterolemia daily 5-40mg of pravstatin was administred in 30 patients after 4 weeks' wash-out and followed in 4 week-intervals up to 12 weeks. 1) Total cholesterol(TC) was decreased from 247.3+/-24,7mg/dl to 216.6+/-34.8mg/dl after 4 weeks, 214.3+/-36.7mg/dl after 8 weeks and 212,5+/-36.1mg/dl after 12 weeks(p,0.001, respectively). 2) Triglycrride(TG) was decreased from 191.3+/-77.9mg/dl to 161.4+/-61.4mg/dl after 4 weeks(p<0.005),155.4+/-74,8mg/dl after 8 weeks (p<0.05) but after 12 weeks the level of triglyceride was 165.5+/-70.3mg/dl, not significantly different from the basal level. 3) LDL-C was decreased from 155.0+/-29.3mg/dl to 129.8+/-34.4mg/dl after 4 weeks. 132.0+/-32.4mg/dl after 8 weeks and 125.9+/-38.1mg/dl after 12 weeks (p<0.01. respectively). 4) HDL-C was not significantly changed during the trial. 5) TC/HDI-C ratio was decreased from 4.8%+/-1.3 to 4.1+/-0.9 after 4 weeks. 4.3.+/-0.9 after 8 weeks and 4.1+/-1.1 after 12(p<0.01.respectivcly). 6) LDL-C/HDL-C ratio was decreased from3.0+/-1.0 to2.5+/-0.8 after 4 weeks(p<0.01).2.6+/-0.7 after 8 weeks(p<0.05) and 2.4+/-0.9 after 12 weeks(p<0.01). 7) The side effects of pravastatin were mild and transient, including 1 case of nausea, 1 headache, 1 flushing sensation on the face and 2 dizziness. 8) The laboratory studies including serum transaminases,uric acid, creatinine, creatine phoshokinase and blood glucose were not changed significantly. These results suggested that pravastatin is an effective and relative safe hypolipidemic agent in Korean adult patients with hypercholesterolemia.