AIM To discuss about the perioperative problems encountered in patients with internal biliary fistula (IBF) caused by cholelithiasis. METHODS In our hospital, 4,130 cholecystectomies were carried out for symptomatic cholelithiasis from January 2000 to March 2004 and only 12 patients were diagnosed with IBF. The perioperative data of these 12 IBF patients were analyzed retrospectively. RESULTS The incidence of IBF due to cholelithiasis was nearly 0.3%. The mean age was 57 years. Most of the patients presented with non-specific complaints. Only two patients were considered to have IBF when gallstone ileus was observed during the investigations. Nine patients underwent emergency laparotomy with a pre-operative diagnosis of acute abdomen. In the remaining three patients, elective laparoscopic cholecystectomy was converted to open surgery after identification of IBF. Ten patients had cholecystoduodenal fistula and two patients had cholecystocholedochal fistula. The mean hospital stay was 13 d. Two wound infections, three bile leakages and three mortalities were observed. CONCLUSION Cholecystectomy has to be performed in early stage in the patients who were diagnosed as cholelithiasis to prevent the complications like IBF which is seen rarely. Suspicion of IBF should be kept in mind, especially in the case of difficult dissection during cholecystectomy and attention should be paid in order to prevent iatrogenic injuries.