Laparoscopic cancer surgery has been reported to facilitate tumor dissemination. In our experience with 158 laparoscopic cholecystectomies, we encountered 2 cases (1.3%) of unsuspected gallbladder cancer. We report these 2 cases to illustrate the disadvantages of laparoscopic tumor resection. In Case 1, a 60-year-old woman with symptomatic cholecystolithiasis underwent a laparoscopic cholecystectomy revealing an unsuspected gallbladder cancer (pT2). Five months later, localized peritoneal carcinomatosis developed in the right subphrenic space, and she died from disseminated disease 19 months postoperatively. Laparoscopic manipulation may have caused the unusual, localized seeding. In Case 2, laparoscopic cholecystectomy was initiated for a polypoid lesion of the gallbladder in a 69-year-old man. When laparoscopy revealed a concomitant cancer (pT3), resection was converted to an open radical cholecystectomy. He remains alive without evidence of disease 31 months postoperatively. Conversion to open surgery may have contributed to the favorable outcome. The contrast between the 2 cases suggests that laparoscopic cholecystectomy should be converted to open surgery whenever malignancy is suspected. Surgeons should note that laparoscopic resection may disseminate cancer.