Background: The efficacy of maze procedure for treating atrial fibrillation (AF) has been well documented. Recently, mini-thoractomy has been widely accepted for the maze procedure. However, there has been no comparative study to show the results between mini-thoracotomy and sternotomy. Methods: We compared the early results of the maze procedure using mini-thoracotomy (TM) with sternotomy(SM). Forty eight consecutive TM patients underwent the maze procedure via right mini-thoracotomy using AESOP 3000짰 system. They were matched with SM patients in age, sex, left atrium(LA) dimension > 60 mm, duration of AF >10 years and etiology of mitral valve disease. LA reduction plasty was performed in both groups(TM: 52.1%, SM: 58.3%). All patients were operated by a single surgeon and perioperative data had been collected prospectively. Results: There was one early death(2.1%) and two late deaths(4.2%) in SM whereas no mortality in TM. No postoperative bleeding was noted in both groups. The postoperative hospital stay(P = 0.001) and aortic cross clamping time(P = 0.046) were shorter in TM. Between the two groups, no significant difference was observed in the need for ardioversion, pacemaker insertion and antiarrhythmic medication(P>0.1). LA size was similarly decreased in both groups(TM: 12.0 짹 8.9mm, SM: 13.0 짹 11.8mm, P=ns). Trans-mitral A wave(TM: 91.7%, SM: 85.4%), sinus rhythm restoration rate at last follow up(TM: 89.6%, SM: 87.5%) were comparable between two groups. Conclusions: Maze procedure using mini-thoracotomy provided shorter hospital stay than sternotomy patients however sinus rhythm restoration rate and reduction in LA size were comparable between the two groups.