Injury of the gallbladder after blunt abdominal trauma is rare. Isolated contusion of the gallbladder is exceptional because of its anatomical localization. It is protected by the liver, intestines, the omentum, and ribs. Its clinical presentation is often insidious, the reason why the diagnosis is often made during an exploring laparotomy. The delayed diagnosis is often responsible for high morbidity and mortality. The early diagnosis is thus essential but still remains a challenge. We report a case of isolated perforation of the gallbladder after blunt abdominal trauma in a 15-years-old boy found at the stage of generalized peritonitis. The exploratory laparotomy leads to diagnosis and treating the lesion by cholecystectomy.