Abstract: Objective To introduce a new technique: transthoracic closure of perimembranous ventricular septal defect (VSD) without cardiopulmonary bypass (CPB) under transesophageal echocardiography (TEE）guidance, and summarize the clinical experiences and midterm followup results. Methods A total of 136 patients with perimembranous VSD, 3 months to 15 years averaging 1.8 years, underwent transthoracic device closure. The weight of these patients ranged from 4.0 to 26.0 kg with an average weight of 12.7 kg. The diameter of their VSD ranged from 3 to 12 mm averaging 5.1 mm. A small transthoracic incision (34 cm incision by inferior sternotomy or 23 cm transverse incision in the third intercostal space) was made and the best location for right ventricular puncture was chosen and the delivery pathway was established under TEE guidance. Proper devices were delivered and then deployed to close the defect. Patients were followed up closely with a standard protocol, arranged for echocardiography, electrocardiogram and chest Xray film. Results In all the cases, 131 cases of VSD (96.3%) were successfully closed. The procedure time was less than 90 minutes and the implanting time was 5.42 minutes (16.3±5.7 min). Symmetrical devices were implanted into 89(67.9%) of the 131 patients and the other 42 patients (32.1%) were closed with asymmetrical ones. The result of TEE soon after operation showed that 3 patients had tiny residual shunt, 4 had new trivial and mild tricuspid regurgitation (TR). However, no TR worsening, aortic regurgitation (AR), complete atrioventricular heart block, or left or right outflow tract obstruction was detected in all patients. One patient 〖CM(159mm〗with transient atrioventricular block restored to sinus rhythm after 3 days of medical treatment. Five cases (3.7%) were converted to conventional open heart repair during the operation. Followup was done to all the patients for a period ranged from 6 months to 30 months (18.3±6.6 months). Tiny residual shunt in the 3 cases mentioned above vanished during the followup period. No new TR, AR, hemolysis, thrombosis, dislocation of the devices, or outflow stenosis was detected postoperatively. The tiny incision caused less psychologic depression. Conclusion Minimally invasive transthoracic device closure of VSD without CPB is a simple, effective and safe intervention under guidance of TEE for most of perimembranous VSD patients. The short and midterm clinical outcomes are promising. Longterm followup is indispensable.