【Abstract】 Objective: To investigate the causes and prevention measures of conversion from Laparoscopic Cholecystectomy(LC) to Open Cholecystectomy(OC). Methods: Retrospective analysis of 4505cases of conversions to laparotomy out of 99cases of LC( 2 .2%) in our hospital from September2005 years to September 2010. Results: The clinical data revealed that the causes of conversion included severe adhesion in abdominal cavity or adhesion between the gallbladder and neighboring tissues，disturbed anatomy and adhesion in Calot’s triangle, a bile duct injury, Gallbladder neck stone impaction, Mirizzi syndrome(type II), bleeding, and cholecystoduodenal fistula and others. The conversion to open surgery was successfully completed in all the 99 cases. No complication was encountered. Followed up examinations for 2 years showed no bile duct stenosis. Conclusion: Comprehensive assessment of the preoperative condition and gallbladder local situation, proper selection of patients, improving the skill of operators, familiar with biliary anatomic variations and using of intraoperative preventive measures are the keys to minimize the rate of conversion to open key.