Lumbar hernia is an uncommon abdominal wall hernia. Acute abdominal wall hernias, particularly lumbar hernias, are a rare complication of trauma. We present a case of acute lumbar hernia as a direct effect of blunt abdominal trauma. Double-contrast CT scan detected herniation of bowel through an 8-cm right flank defect, which was surgically repaired with a prosthetic patch and omentopexy. In cases of acute traumatic lumbar hernia, immediate exploratory laparotomy with primary repair (when feasible) is recommended.