Coarctation of the aorta without intracardiac structural anomaly is uncommon and is rarely detected during early infancy. We report here a case of simple coarctation of the aorta in a male newborn who was initially treated for postnatal transient tachypnea. A disparity in blood pressure between the upper and lower extremities prompted echocardiographic examination focused on the aortic isthmus. Heart failure due to afterload mismatch was confused with neonatal tachypnea in the first days after admission. Surgical repair was successfully performed, and the postoperative course was uneventful. Careful physical examination was the key clue to the correct diagnosis of this unusual condition in our patient.<br>