Intravenous propafenone (1 mg/Kg in 3 min) has been administered to 14 patients with recent atrial fibrillation. The sinus rhythm was restored in 7 patients within 30 min after the injection. The left atrial size, evaluated by M-mode echocardiography, was no different in the group of responders, with respect to the non-responders. No adverse effect has been observed. One single patient manifested a long asystolic pause (3860 ms), at the restoration of sinus rhythm. Propafenone appears to be useful in the treatment of recent atrial fibrillation.