Objective: To analyze the preoperative factors contributing to the decision to convert laparoscopic to open cholecystectomy. Methods: Retrospective identification of 324 consecutive patients undergoing laparoscopic cholecystectomy, with univariate and multivariage analysis of the following parameters: age, gender, obesity, previous abdominal surgery, presentation with acute cholecystitis, pancreatitis or obstructive jaundice, gallbladder wall thickening, gallbladder or common bile duct stones. Results: Thirty-nine patients (12\%) underwent conversion to open cholecystectomy. Patients aged over 65 years were four times more likely to require conversion than patients under 50 years of age. Under 50 years of age, males had equal conversion rates to females, and above this age there was a non-significant increased conversion rate in males. Obese patients had higher conversion rates than non-obese patients (23\% versus 9\%, P < 0.003). Thirty-eight percent of patients with choledocholithiasis required conversion. Age, acute cholecystitis and choledocholithiasis independently predicted conversion. A patient aged less than fifty years with neither acute cholecystitis nor choledocholithiasis had a voncersion rate of just 2\%, while almost 60\% of those over 65 years of age with acute cholecystitis or choledocholithiasis required conversion. Conclusion: The parameters of age, acute cholecystitis and choledocholithiasis must be considered in the clinical decision making process when planning laparoscopic cholecystectomy.