Atrial fibrillation (AF) is associated with a significant mortality and morbidity. Microwave (MW) ablation is a new technology for surgical treatment of this arrhythmia. We present our preliminary experience with MW ablation in patients with AF who underwent a concomitant open-heart surgery. From October 2001 to March 2002, a total of 10 patients underwent MW ablation of AF and an open-heart surgery at the Department of Cardiovascular Surgery of the University of Bologna. All patients experienced chronic AF and the mean duration of rhythm disturbance was 82.8 months, ranging from 24 to 360 months. There was no complication related to the surgical procedure. The overall survival rate, after discharge, was 100% and sinus rhythm recovery rate was 77.8% after a mean follow-up time of 12.4 months (10-15 months). Our preliminary results show that MW ablation may be a very effective way of converting patients with atrial fibrillation into sinus rhythm.