The presence of appendix within a femoral hernia is a rare condition in an incarcerated femoral hernia. It has a characteristic groin mass, and the diagnosis of appendicitis is mainly made intraoperatively. A specific imaging appearance (ultrasonography, computed tomography [CT]) allows accurate prospective diagnosis. The recognition of this rare femoral hernia helps us to choose appropriate therapeutic approach. We report a case of an 81-year-old woman who present with painful and nonreducible groin mass. The ultrasonography and CT characteristic imaging features successfully diagnosed de Garengeot hernia. To our knowledge, this is the first description of a combination of CT and ultrasound in the preoperative diagnosis.