Tricyclic antidepressant drugs are known to cause often electrocardiographic abnormalities and to induce sometimes cardiac rhythm disturbances. We report a case of a patient on antidepressant therapy (Desipramine Hydrochloride, 50 mg/die, and Dothiepin Hydrochloride, 150 mg/die), without any underlaying heart disease, admitted to our Coronary Care Unit for recurrent syncopal episodes. An ECG on admission showed Sinus Tachycardia with Ectopic Ventricular Beats and recurrent runs of Torsade de Pointes, a distinctive form of Ventricular Tachycardia. Lignocaine i.v. was only transiently effective. Both Isoprenaline and Atropine Sulphate i.v. were uneffective. Ventricular Fibrillation occurred and cardioversion was achieved by a single DC shock. Amiodarone i.v. and electrical overdrive only temporarily suppressed ventricular arrhythmias. Magnesium Sulphate i.v. (bolus + infusion) induced a definitive suppression of Torsades de Pointes. One day later no more arrhythmias were present.