There is some safety concern about transesophageal echocardiography (TEE) when it is used routinely during cardiac operations. The purpose of this investigation was to study the incidence of intraoperative TEE-associated complications in adult cardiac surgical patients. The study population comprised 6255 consecutive adult cardiac surgical patients with intraoperative TEE examinations. TEE-associated complications occurred in 25 patients (0.4%). Most of these complications consisted of oropharyngeal mucosal bleeding (15/25, 60%). Esophageal perforation occurred in one patient. Two patients experienced upper gastrointestinal bleeding. Seven patients experienced dental injuries, and TEE probe insertion failed in 10 patients. We conclude that intraoperative TEE-associated complications in cardiac operations is very low; the complication rate we found was comparable to previously reported values. [J Formos Med Assoc 2007; 106(1):92-95]