Amiodarone, a class III antiarrhythmic agent, is a potent vasodilator in vivo. Its main metabolite, N-desethylamiodarone, contributes to the antiarrhythmic action of amiodarone after long-term treatment. It is unknown whether N-desethylamiodarone has acute vascular effects. The aim of this study was to explore the mechanism of action of N-desethylamiodarone in human hand veins.