Rimonabant is the first of a new class of selective cannabinoid receptor-1 blockers. It reduces the overactivity of the endocannabinoid system, improving lipid and glucose metabolism and regulating food intake and energy balance. In four randomised, double-blind clinical trials in overweight or obese adults with or without type 2 diabetes and/or dyslipidaemia, oral rimonabant 20mg once daily reduced weight and waist circumference to a significantly greater extent than placebo. A significantly greater proportion of rimonabant than placebo recipients achieved the clinically significant weight-loss target of > or =5% or > or =10% of initial weight. Rimonabant was associated with significant improvements in glycaemic control relative to placebo, with approximately equal to 57% of the reduction in glycosylated haemoglobin being independent of the effects of weight loss in one trial. Improvements in other cardiometabolic risk factors (i.e. increases in high-density lipoprotein-cholesterol [HDL-C] and decreases in triglyceride [TG] levels) were significantly greater with rimonabant than with placebo. The improvement in lipid profile also demonstrated a weight-independent effect, with approximately equal to 47-58% of the improvement in HDL-C and TG being beyond that expected through weight loss alone. Rimonabant was generally well tolerated, with most adverse events considered mild to moderate in severity.