Lost gallstones after accidental opening of the gallbladder during cholecystectomy usually under laparoscopy, can cause late complications. Intra-abdominal abscess is the most frequent and the diagnosis is based on imaging techniques (abdominal ultrasound or computed tomography scan). Surgical drainage with gallstones removal seems to be the best approach, due to the fact that a simple percutaneous drainage has a high failure rate. However, a posterior abdominal wall abscess as the initial manifestation of intra-abdominal abscess due to retained gallstones is uncommon, and this prompted us to report this case.