Since the introduction of fenofibrate to European clinical practice in 1975, some 6.5 million patient-years of experience in the treatment of hyperlipidemia have been accumulated. A review of results of clinical trials shows fenofibrate to have a broad spectrum of lipid-lowering activity, reducing the total cholesterol level by 20–25% in type Ha patients and triglycerides by 40–60% in type lib and IV patients. High levels of low-density lipoprotein cholesterol are reduced and, where low at baseline, high-density lipoprotein levels are increased. An associated activity is a 10–28% reduction in serum uric acid levels. Adverse reactions in the mostly open clinical trials ranged from 2–15 %; mild gastrointestinal problems dominated, and occurred with much the same frequency in the placebo-treated groups of controlled trials. There are also reports of fatigue, headache, loss of libido, dizziness, and insomnia. Some excess of skin rash emerged as the only statistically significant unwanted clinical effect in one placebo-controlled trial. Biochemically, there are occasional fluctuations in serum transaminase values, while γ-glucuronyl transferase and alkaline phosphatase are often decreased, all without apparent clinical significance. Lithogenicity of the bile is often increased above pretreatment levels, but there is no evidence from trials or postmarketing surveillance that the use of fenofibrate is associated with an increase of gallstone formation.