Introduction: Laparoscopic cholecystectomy is the gold standard procedure for gall stone disease. Few cases of acute calculous cholecystitis require conversion to open procedure which can increase the morbidity and financial burden to patient. Hence, through this study we are trying decide regarding the parameters which would help to assess the patient preoperatively and predict the outcome of laparoscopic cholecystectomy. Aims and Objectives: To assess the preoperative parameters to predict conversion of laparoscopic cholecystectomy to open cholecystectomy in patients with acute calculous cholecystitis. Materials and Methods: A prospective study was conducted at a tertiary care hospital. Study was conducted after obtaining ethical committee clearance and informed consent from patients. 100 patients were included in the study. Results: 100 patients of acute calculous cholecystitis were taken for laparoscopic cholecystectomy of which 80 patients successfully completed the procedure and remaining 20 patients had to undergo conversion to open procedure. Conclusion: Male gender, older age, patients with higher pain (VAS) score, raised TLC, raised total bilirubin, raised serum ALP are associated with failure of laparoscopic cholecystectomy. Keywords: Acute calculous cholecystitis; Cholecystectomy; Laparoscopic cholecystectomy; Failure of laparoscopy; Conversion to open cholecystectomy.