A 42-year-old female suffered annulo-aortic ectasia (AAE) and mitral regurgitation associated with Marfan's syndrome was successfully treated by a modified Bentall procedure combined with mitral valve replacement (MVR) under continuous warm blood cardioplegia (CWBC). With the patient under total cardiopulmonary bypass and myocardial protection with CWBC, MVR with 27 mm mechanical valve was first done, followed by the total replacement of the aortic root with a composite graft made of vascular graft and an aortic mechanical valve. Anastomosis of the composite graft to the aortic valve annulus was made to guarantee a watertight closure using numerous interrupted mattress sutures and three pieces of Teflon felt strips to the annulus. Both coronary arteries were reconstructed by means of the “Interposition Graft Method” which interposes two short grafts between the composite graft and both coronary ostia. In spite of long time aortic cross clamp (235 min), cardiac function was recovered excellenthy and a peak CK-MB value was very low (23 IU/L) in the early postoperative period. Thus, CWBC provided a satisfactory myocardial protective effect. It was suggested that the modified Bentall procedure combined with MVR using CWBC was an effective therapy for a patient with AAE and mitral regurgitation associated with Marfan's syndrome.