Objective:To compare the outcomes of minimal invasive mitral surgery under minimal extracorporeal circulation with those under conventional middle sternotomy. Methods:Ninety patients with mitral stenosis and/or insufficiency,who need mitral repair or replacement,were randomized into minimal invasive (Group A,45 cases,minimal right thoracotomy under minimal extracorporeal circulation,MECC) or conventional middle sternotomy (Group B,45 cases). The following items are recorded and then compared:cardiopulmonary bypass time,aortic cross clamp time,the amount of blood lose during surgery,blood transfusion,peri-operative chest drainage,time of intubation and ICU stay post-operation. Results:There were no major complications and operative death in both groups. Both CPB time and cross clamp time in group A were longer then in Group B (P < 0.05). But the bloods lose during surgery,the amount of chest drainage and blood transfusion peri-operatively were significantly lower in Group A than in Group B (P < 0.05,P < 0.01,P < 0.05,respectively). The intubation time and ICU stay after surgery were obviously shorter in group A than in group B (P < 0.05),with lower hospital cost in group A. (P < 0.01). Conclusion:Mitral surgery through mini-thoracotomy under MECC improves the quality of surgery on following aspects:trauma,lower blood lose and transfusion,recovery,cost-effective,cosmetic effect and patients satisfaction even with relative longer CPB and cross clamp times.