A catalogue of antiobesity agents came and went during the last century. The current weight loss agents orlistat and sibutramine are now to be joined by rimonabant, a cannabinoid-1 (CB1) receptor antagonist that acts centrally to decrease appetite and peripherally to reduce lipogenesis in adipose tissue. Use of rimonabant is based on evidence that the endogenous cannabinoid system is overactive in obesity, mainly due to increased expression of CB1 receptors. Weight loss attributed to rimonabant (about 5 kg over one year) was associated with improved insulin sensitivity, reduced triglyceride and increased high density lipoprotein cholesterol. Like other antiobesity agents rimonabant should be used as an adjunct to lifestyle advice. Although there are several potential antiobesity agents in development these are mostly at an early stage of clinical evaluation.