The anatomic closeness of heart and thyroid gland makes it feasible to operate on both organs simultaneously if required. Between January 1988 and February 1994 we did simultaneous procedures on heart and thyroid gland in 14 patients. We did not see any procedure-specific complications. The cumulative risk of the combined operation seems to be less than in the two stage procedure, because of the better exposure of the thyroid. The main advantage for the patient is the avoidance of a second intervention. Because of the high frequency of thyroid diseases liable for operation endocrinological diagnostics should be performed in all patients undergoing cardiac surgery. The indication for a simultaneous intervention should be made generously in order to avoid a second operation.