Gallbladder congenital duplication is a rare disease difficultly diagnosed preoperatively. Eight days after a laparoscopic cholecystectomy a 72-year-old man, complaining of abdominal pain and vomiting, presented to our emergency department. Ultrasound and computer tomography (CT) scans demonstrated a gallbladder-like structure with a 12-mm diameter stone and a subhepatic fluid collection. During an endoscopic retrograde cholangiopancreatography, a probably second gallbladder with a fistula of the posterior wall was filled with contrast. Laparoscopic exploration confirmed a missed gallbladder, which was successfully removed. Histologic diagnosis of cholecystolithiasis and chronic cholecystitis was made. The postoperative course was uneventful. Symptomatic double gallbladder should be considered also during the complicated postoperative course after the laparoscopic cholecystectomy and laparoscopic reoperation is feasible.