Extended-release (ER) niacin (nicotinic acid)/laropiprant is a once-daily fixed-dose combination tablet that has been evaluated (with or without an HMG-CoA reductase inhibitor [statin]) in the treatment of adults with dyslipidaemia or primary hypercholesterolaemia. Niacin (vitamin B3) is a lipid-modifying drug and laropiprant is an anti-flushing agent, which reduces flushing induced by niacin. In a randomized, double-blind, placebo-controlled, multicentre, 24-week trial, a significant (p < 0.001) reduction (18.4%) in plasma low-density lipoprotein cholesterol (LDL-C) levels (primary endpoint) was achieved with ER niacin/laropiprant 2000 mg/40 mg once daily (after an initial 4-week 1000 mg/20 mg once-daily regimen) compared with placebo (weeks 12-24) in adults with primary hypercholesterolaemia or mixed dyslipidaemia. ER niacin/laropiprant 2000 mg/40 mg plus simvastatin 20 mg or 40 mg once daily (after an initial 4-week lower-dose regimen) produced significant (p < 0.05) improvements, from baseline, in LDL-C levels (primary endpoint) compared with once-daily ER niacin/laropiprant 2000 mg/40 mg or simvastatin alone at week 12 in a randomized, double-blind, multicentre, factorial trial in adults with primary hypercholesterolaemia or mixed dyslipidaemia. The incidence and intensity of flushing (an efficacy endpoint) were significantly (p < 0.05) reduced with ER niacin/laropiprant compared with ER niacin in randomized trials. ER niacin/laropiprant, alone or in combination with a statin, was generally well tolerated for up to 24 weeks by adults with dyslipidaemia or primary hyercholesterolaemia.