A case of a heterotopic intrathoracic lobe of the liver connected through a normal diaphragm to the main organ by a vascular and biliary pedicle is described. Eight similar cases reported in the literature are reviewed and a comparative evaluation is undertaken to elucidate the correct clinical diagnosis and the indications for operative exploration. Because the occurrence of ectopic supradiaphragmatic hepatic tissue should be considered, it is believed that the preoperative evaluation of a solid, smooth lump in the diaphragmatic region should include gallium liver scans prior to invasive procedures.