--Obesity is an important healthcare issue. --Recent research has led to insights into the role of the endocannabinoid system in the regulation of body weight. --Rimonabant is a CB1-endocannabinoid-receptor antagonist. --Four trials were published recently on the efficacy and safety of rimonabant in the treatment of people with obesity. --When combined with a hypocaloric diet, rimonabant 20 mg/day was more effective than placebo in achieving and maintaining weight loss. In addition, treatment with rimonabant had beneficial effects on insulin resistance, HDL-cholesterol and hypertriglyceridaemia. --There is concern regarding the increased incidence of depression during treatment. --Whether the beneficial effects of rimonabant on weight reduction and cardiovascular risk factors translate into a reduction in cardiovascular morbidity and mortality remains to be established in large phase III trials.