The discovery of a thoracic kidney in adult patients can lead to three diagnoses, yielding different prognoses and treatment. It can either mean traumatic or congenital diaphragmatic hernia, or a congenital ectopic kidney. Intrathoracic herniation of the left kidney trough a left diaphragmatic rupture is an exceptional discovery. We report the case of a 44 year-old man who met with a car accident 20 years ago, and presented abdominal pain. CT-scan showed an intrathoracic herniation of the left kidney trough a left posterior diaphragmatic rupture. Laparoscopic approach in lateral position showed a traumatic hernia of the left costo-diaphragmatic hiatus only containing the left kidney and its pedicle. After reduction of herniated left kidney into the abdomen, the hiatus was closed by non-resorbable prosthetic mesh. Postoperative course was uneventful.