OBJECTIVE Recently, closed mitral commissurotomy (CMC) has been reexplored due to the concepts of less invasive valvular surgery. The feasibility of closed mitral commissurotomy via port access or limited thoracotomy by aid transesophageal echocardiography (TEE) was investigated in this clinical study. METHODS Between August 1996 and April 1998, 42 patients (32 women, ten men with a mean age of 36.2+/-7.8 years) underwent less invasive CMC at the Kosuyolu Heart and Research Hospital. CMC procedure were done through a limited (12-16 cm) thoracotomy incision in 23 patients, a very limited or mini thoracotomy incision (7-8 cm) in 11 patients and port access by aid TEE in eight patients. Preoperative mean mitral valve area was calculated as 1.19+/-0.13 cm2 and mean mitral valve gradient was measured as 14.8+/-3.2 mmHg. TEE provided information about the mitral valve anatomy and functions during the procedure in all patients. RESULTS Commissurotomy was successfully performed in all patients. In eight patients, a Tubbs dilator was inserted via port access at the 6th intercostal space from a 3-cm incision. Incision by guidance of TEE and CMC could be performed without thoracotomy in five patients. In three patients of the port access group, a very limited thoracotomy was required to perform CMC by digital guidance. Postoperative mean MVA was 2.37+/-0.29 cm2, minimal mitral gradient was 5.3+/-1.7 mmHg. In eleven patients, minimal mitral regurgitation was observed. The operations and postoperative period were free of complications in all patients. Following an average 12+/-2.8 h intensive care unit period, all patients were discharged after an average of 3.4+/-0.8 days of hospitalization. CONCLUSIONS Limited thoracotomy has less detrimental structural effects in patients. Port access by aid TEE approach to CMC may offer less invasiveness, lower cost effectiveness and be an alternative to percutaneous balloon mitral valvotomy.