Complete and optimal visualization of the mitral apparatus is a prerequisite for accurate repair or replacement of the mitral valve. A vertical left atriotomy just posterior to the interatrial groove is the most commonly used approach. However,exposure can be difficult under certain circumstances,such as small left atrium or reoperation. Other approaches have been advocated to deal with this difficult situations. We used an extended transseptal approach in 10 patients and good clinical results and excellent educational effects were obtained. The extended transseptal approach combines two semicircular atrial incisions circumscribing the tricuspid and mitral annuli anteriorly and superiorly,allowing exposure of the mitral valve by deflecting the ventricular side using stay sutures. The right atrium is opened anteriorly along the atrioventricular sulcus. The atrial septum is incised vertically through the fossa ovalis. Right atrial and septal incisions are joined at the superior end of the interatrial septum and extended across the dome of the left atrium to the left atrial appendage. The mitral valve was replaced in all 10 patients. Four of 10 patients had other simultaneous valve procedure: one had aortic valve replacement: 2 underwent tricuspid annuloplasty: 1 had aortic valve replacement and tricuspid annuloplasty. There was no hospital death and complication. Among the 5 patients who had atrial fibrillation preoperatively,4 had atrial fibrillation postoperatively,1 converted to sinus rhythm. The five patients who were in normal sinus rhythm preoperatively remained in sinus rhythm after replacement. A review of our results with this approach confirms the efficacy and safty of this method. So we recommanded this approach for routine mitral valve procedure,especially difficult situations,such as a small left atrium or the redo operation.