We report port site and distant metastases of unsuspected gallbladder cancer after laparoscopic cholecystectomy diagnosed by positron emission tomography (PET) in two patients. Patient 1, a 72-year-old woman was diagnosed as cholelithiasis and cholecystitis and received laparoscopic cholecystectomy. Unsuspected gallbladder cancer was discovered with histological result of well-differentiated squamous cell carcinoma of the gallbladder infiltrating the entire wall. A PET scan using F-18-fluorodeoxyglucose (FDG-PET) before radical resection revealed residual tumor in the gallbladder fossa and recurrence at port site and metastases in bilateral hilar lymph nodes. Patient 2, a 69-year-old woman underwent laparoscopic cholecystectomy more than one year ago with pathologically confirmed unsuspected adenosquamous carcinoma of stage pT1b. At 7-mo follow-up after surgery, the patient presented with nodules in the periumbilical incision. Excisional biopsy of the nodule revealed adenosquamous carcinoma. The patient was examined by FDG-PET, demonstrating increased FDG uptake in the right lobe of the liver and mediastinal lymph nodes consistent with metastatic disease. This report is followed by a discussion about the utility of FDG-PET in the gallbladder cancer.