The Mustard operation to correct the abnormal physiology associated with transposition of the great arteries (TGA) was introduced in 1964. This study examines the intermediate outcomes of the Mustard operation. Methods: Included in the study were 6 patients who underwent the Mustard operation between 1991 and 2002. Demographic characteristics, operative data, postoperative results, and intermediate-term outcomes of patients were retrospectively reviewed. Results: There was no operative mortality but there was one late death. One patient who was born with sick sinus syndrome required pacemaker implantation. The other four survivors were in sinus rhythm. There was no baffle-related systemic or pulmonary venous obstruction in the survivors. Although mild tricuspid regurgitation developed in most patients, no patient had right ventricular dysfunction. At the latest follow-up, four patients are in NYHA class I and one patient is in NYHA class II. Conclusions: The intermediate outcomes of the Mustard operation in these patients are satisfactory. However, long-term follow-up is mandatory to determine the fate of these Mustard patients. The Mustard operation may be a reasonable alternative in the surgical treatment of TGA if an arterial switch operation is not feasible or is technically difficult.