Antazoline is a first generation antihistaminic agent with chinidin-like properties. When administered intravenously, antazoline exerts a strong antiarrhythmic effect on supraventricular arrhythmia especially on atrial fibrillation (AF) facilitating rapid conversion to sinus rhythm. Despite relative lack of published data antazoline is marketed in Poland and widely used in cardiology wards and emergency rooms due to its efficacy, safety and rapid onset of action within minutes of administration.