The cholesterol ester-transferase protein inhibitor anacetrapib reduced LDL-cholesterol levels in patients with heterozygous familial hypercholesterolaemia already receiving optimal lipid-lowering therapy. LDL-cholesterol levels were reduced in patients who received 100 mg oral anacetrapib for 52 weeks compared with those who were assigned placebo (placebo-adjusted percentage change −39.7%, 95% CI −45.7 to −33.7; P <0.001). This study shows that anacetrapib in addition to current lipid-lowering treatments can decrease atherogenic lipids in circulation, but whether anacetrapib can prevent cardiovascular events remains to be determined.