Rimonabant is a selective cannabinoid-1 receptor blocker that has been shown to reduce weight and improve several cardiovascular risk factors in obese patients.1 2 3 4 In 2004 an editorial stated that rimonabant was “promising in the prevention of cardiovascular events in obese patients.”5 In a review article, although the frequent occurrence of psychiatric adverse events was mentioned, rimonabant was still recommended in the treatment of overweight patients with type 2 diabetes and metabolic syndrome in whom lifestyle changes are not sufficiently effective. 6 7 The drug was recently withdrawn by the European Medicines Agency (www.nice.org.uk/TA144), but it is likely to remain available over the counter and through the internet. We report two cases of atrial fibrillation in overweight patients treated with rimonabant.