Rimonabant (Acomplia) is the first selective CB1 receptor blocker of the endocannabinoid system. It has been evaluated in the RIO ("Rimonabant In Obesity and related disorders") programme including above 6.600 overweight/obese patients with or without comorbidities followed for 1 to 2 years. Compared to placebo, rimonabant 20 mg/day consistently increases weight loss, reduces waist circumference, increases HDL cholesterol, lowers triglyceride levels, diminishes insulin resistance, and reduces the prevalence of metabolic syndrome. In patients with type 2 diabetes, rimonabant also diminishes HbA1c levels, an effect confirmed in the recent SERENADE trial. Almost half of the metabolic effects occurs beyond weight loss, suggesting direct peripheral effects of rimonabant. Rimonabant is indicated in Europe as an adjunct to diet and exercise for the treatment of obese patients, or overweight patients with associated risk factor(s), such as type 2 diabetes or dyslipidaemia.