Among the drugs recommended to prevent recurrences of atrial fibrillation after external electric shock, antiarrhythmic agents of classes Ia (quinidine, disopyramide), Ic (cibenzoline, flecainide, propafenone) and III (sotalol) seem to have the same effectiveness in maintaining the sinus rhythm in about 50 percent of the cases after 6 months and one year. Amiodarone, seldom used as first-line treatment, appears to be the most effective drug. The percentage of side-effects requiring discontinuation of treatment is the same for all drugs (about 10 percent). All these drugs have potential proarrhythmic effects. In case of recurrence electric shocks can be repeated in some special cases. The therapeutic strategy according to the clinical context (atrial fibrillation of vagal nerve or catecholergic origin, normal or altered left ventricular function) is discussed.