Cardiac surgery in patients with a positional anomaly of the heart is technically challenging, and very few reports exist of such surgery in patients with dextrocardia. A 73-year-old woman in whom dextrocardia with situs solitus had been diagnosed at a young age, presented with palpitation and shortness of breath due to significant mitral valve insufficiency. Cardiopulmonary bypass (CPB) was initiated through aortic, superior vena cava, and inferior vena cava cannulae. The use of a heart positioner simplified and made safe the initiation of CPB. A left-sided left atriotomy provided excellent exposure of the mitral valve, and mitral valve replacement (MVR) was safely performed with a 25 mm St. Jude Medical mechanical prosthesis. The postoperative course was uneventful. In patients with dextrocardia requiring cardiac surgery, it is important to consider the appropriate surgical strategy. Approaching the mitral valve through a left-sided left atrial incision seems to provide excellent exposure for MVR.