This study was designed to evaluate the usefulness of performing transesophageal echocardiography (TEE) during percutaneous mitral balloon valvulotomy (PMBV). TEE was performed in 35 consecutive patients with symptomatic severe mitral stenosis during PMBV (group A). Another group of 27 patients with mitral stenosis who underwent PMBV without TEE was used for comparison (group B). TEE was most helpful in guiding transseptal puncture, aiding in proper positioning of the balloon during the dilatation procedure and enabling early detection of complications. The results show that PMBV when aided by TEE has a tendency to decrease the frequency of significant mitral regurgitation without compromising the final mitral valve area. TEE decreased the x-ray exposure time and was well-tolerated. Thus, TEE provides information that makes this interventional catheterization procedure safer and easier to perform.