Objectives: Left atrial volume (LAV) and atrial fibrillation (AF) are important predictors of outcome after mitral valve (MV) surgery in patients with chronic mitral regurgitation (MR). However data on LA reverse remodelling after antiarrhythmic procedures during MV surgery for chronic MR are scarce. Methods: Clinical and echocardiographic parameters were prospectively collected in 69 consecutive patients (aged 53짹13 years, 39 men) with severe mitral regurgitation who underwent MV surgery (26 in MV replacement and 43 in MV repair). Atrial function was assessed by M-mode, 2-dimensional echocardiography, transmitral Doppler, tissue Doppler velocity imaging. LA maximal volume was measured at left ventricular (LV) end systole (area-length method). The percentage of LAV change was calculated. Results: Sinus rhythm was restored in 21 (67%) of 31 AF patients underwent anti arrhythmic procedure (MAZE op or pulmonary vein obliteration ect.) with MR surgery. LA volume decreased from 205짹91 to 123짹63 ml (p < 0.001) after surgery in all patients. LA reverse remodelling was more prominent in patients who were converted to sinus rhythm (percentage of LA volume change -38짹27 vs -25짹20, p < 0.004). Left atrial mechanical function, assessed by A wave velocity and the annular motion, improved significantly after MV surgery, especially in patients with sinus conversion (p < 0.002) Conclusion: Antiarrhythmic procedure of the left atrium during MV surgery for MR with AF significantly improves LA function and LA reverse remodelling. On the basis of its efficacy and safety, routine use of antiarrhthmic procedure during mitral valve surgery may be justified.