Ezetimibe is a novel cholesterol absorption inhibitor that blocks intestinal absorption of dietary and biliary cholesterol. Data from 1719 patients who participated in two multicentre, double-blind studies of ezetimibe were pooled to evaluate the drug's efficacy and safety in patients with primary hypercholesterolaemia. Following dietary stabilisation, a two- to 12-week washout period, and a four-week, single-blind, placebo lead-in period, patients were randomised to ezetimibe 10 mg or placebo once daily in the morning for 12 consecutive weeks. The primary efficacy endpoint was percent reduction in plasma low-density lipoprotein (LDL)-cholesterol from baseline at endpoint. Ezetimibe reduced LDL-cholesterol by a mean of 18.2% compared with an increase of 0.9% with placebo (P<0.01) and resulted in favourable, statistically siqnificant chanqes in HDL-cholesterol, triglycerides and apo B. The response to ezetimibe was consistent across all subgroups analysed. Ezetimibe was well tolerated, with a safety profile similar to placebo.