One of the uncommon congenital variations is intrathoracic rib which a normal, a bifid, or an accessory rib lies within the thoracic cavity that is founded accidentally. Clinically, in most cases they are without symptoms; however, it may cause intrathoracic problems therefore it is important for radiologists and physicians to identify to prevent of excessive intervention and treatment during imaging diagnostic techniques of thoracic problems. In this report, we provide the case of a rare presentation of an intrathoracic rib in a 3-year-old boy arising from the inferior portion of a second rib based on findings from computed tomography. To our knowledge, this is only the second reported case of this type of intrathoracic rib that demonstrated with computed tomography.