BACKGROUND: The ciprofibrate, 3rd generation fibrate derivative, is known as an effective hypolipidemic drug in both hypercholesterolemia and hypertriglyceridemia. We studied the efficacy and side effects of ciprofibrate dmonotherapy in patients with primary type II and type IV hyperlipidemia. METHOD: Patients who showed 12-hours fasting serum total cholesterol level more than 240mg% and/or serum triglyceride level more than 250mg% were enrolled to diet therapy. After 12 weeks of diet therapy serum lipid profiles were checked and the drug therapy was considered according to the above mentioned guidelines. The ciprofibrate 100mg p.o qd was administrated and the patients had regular follow-up every 6 weeks for 12 weeks. RESULTS: The total study population was 32 patients. Fifteen patients were type II hyperlipidemia and seventeen patients were type IV hyperlipidemia. The drug was well tolerated in all patients. There was mild gastrointestinal side effects in 9% of study patients but no patients discontinued ciprofibrate due to side effects. There was mild and transient serum CK elevation less than 3 times of baslines in 5(15%) patients. The LFT, serum uric acid, BUN and creatinine level did not show any significant changes during therapy. Serum total cholesterol and apolipoprotein B level in patients with type II hyperlipidemia showed significant reduction after 6week of therapy. The mean reduction was 25% and 32% respectively. Serum triglyceride level in patients with type IV hyperlipidemia decreased by 55%. The reduction of total cholesterol more than 25% could be achieved in 50% of type II hyperlipidemia and the reduction of triglyceride more than 25% could be achieved in 93% of type IV hyperlipidemia. CONCLUSION: The ciprofibrate is effective and sage hypolidipemic drug in patients with primary type II and type IV hyperlipidemia.