Gemfibrozil improves lipid and apolipoprotein profiles, particularly very low density lipoprotein (VLDL) triglyceride and high density lipoprotein (HDL) cholesterol levels, in patients with dyslipidaemia when administered at a total daily dose of 900 or 1200 mg. As demonstrated by the Helsinki Heart Study, these effects result in a reduction in some risk factors for coronary heart disease (CHD) and also a 34% reduction in the incidence of this disease after 5 years compared with placebo. Limited data suggest that gemfibrozil has beneficial effects on the fibrinolytic system and may slow the progression of atherosclerosis. Gemfibrozil has shown efficacy in the treatment of patients with type IIa, IIb, III, IV or V dyslipidaemia or hypoalphalipoproteinaemia, especially in patients with elevated triglyceride and low HDL cholesterol levels. It is also effective in patients with non-insulin-dependent diabetes mellitus (NIDDM) and dyslipidaemia and has no detrimental effects on glycaemic control. A small number of studies also showed gemfibrozil to be effective for the control of dyslipidaemia associated with renal failure, transplantation, nephrotic syndrome, arterial occlusive disease or systemic lupus erythematosus. However, patients with pre-existing CHD do not appear to derive the same benefits (reduced CHD mortality) from gemfibrozil therapy as these other patients, although results are based on studies of limited size and number. In general, gemfibrozil has at least similar efficacy to bile acid sequestrants and other fibric acid derivatives. Comparisons with HMG-CoA reductase inhibitors show these agents to produce different effects on lipid profiles from gemfibrozil. Thus, gemfibrozil would be expected to be superior in some patients (those with elevated triglyceride or VLDL cholesterol levels), but HMG-CoA reductase inhibitors should have greater benefits in those with elevated low density lipoprotein cholesterol levels. Thus, in patients with elevated triglyceride levels and low HDL cholesterol levels, and, particularly in patients with NIDDM, gemfibrozil is a useful treatment option, which has been shown to reduce the risk of CHD in middle aged men. However, limited available data prevents the accurate comparison of this agent with HMG-CoA reductase inhibitors in patients with this lipid profile.