With the increasingly widespread acceptance of laparoscopic cholecystectomy (LC), the number of cases of incidental gallbladder carcinoma (GBC) has increased; however, management of incidental GBC is a difficult issue in the absence of established guidelines. The present study aims to evaluate the treatment of patients with incidental GBC diagnosed with LC. We performed a 14-year review of 10 patients with GBC discovered with LC. From April 1991 through March 2004, we performed LC for 1,195 patients at Nippon Medical School Main Hospital. Of these patients, 10 (0.83%) were found to have GBC. Seven patients were women and 3 were men, with a mean age of 61.4 years. Four patients had mucosal tumors (pT1a), 5 had subserosal tumors (pT2), and 1 had a serosal lesion (pT3). Eight of the 10 patients underwent radical surgery. Two patients with pT1a tumors underwent no additional surgery. All 4 patients with pT1a tumors are alive without recurrence. One patient with a pT2 tumor with metastases to the liver and pericholedochal lymph nodes found with additional resection died of recurrence of metastasis to the liver and lung 70 months after LC. One patient with a pT2 tumor died of primary lung cancer 35 months after LC. The remaining 3 patients with pT2 tumors are alive without recurrence 51 to 128 months after surgery. One patient with a pT3 tumor is alive with no recurrence for 9 months. For stage Tis or T1a tumors, LC is sufficient. Patients with T1b tumors should undergo liver-bed resection and lymphadenectomy, and patients with >pT2 tumors should undergo systematic liver resection with lymphadenectomy. Even when incidental GBC diagnosed with LC is advanced, adequate additional surgery may improve the prognosis.