Aim: To investigate whether the neutrophil lymphocyte ratio is a determining factor in the detection of complicated acute calculous cholecystitis.Material and Methods: The study was planned as retrospective and multi-centered. One hundred and twenty patients were divided into 3 groups equally. Group1; patients with symptomatic gall stones having undergone elective cholecystectomy. Group 2; patients having undergone cholecystectomy with acute cholecystitis.Group 3: patients having undergone cholecystectomy with acute complicated cholecystitis. Blood glucose, C-reactive protein, leukocyte, neutrophil, and lymphocyte ratio were recorded from the hospital records in the final laboratory parameters of patients before surgery. ROC nalysis, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), cut-off and AUC values for NLR were calculated.Results: There was a significant difference between the gangrenous cholecystitis group and other groups in terms of white blood cell count values (p = 0.002 and p <0.001).There was a significant difference between the gangrenous cholecystitis group and other groups in terms of CRP values (p <0.001).There was a difference between gangrenous cholecystitis group and normal cholecystectomy group according to the mean glucose values (p = 0.006)According to ROC analysis, sensitivity, specificity, cut-off and AUC values for NLR in terms of gangrenous cholecystitis and acute cholecystitis were,77.50%,67.5%,80.9%,73.8%,6.56 and 0.736, respectively. For gangrenous cholecystitis group and normal cholecystectomy group; these values were 85%, 77.5%, 94%, 87.9%, 4.43% and 0.878%, respectively.Conclusion: The increase in the acute cholecystitis N / L ratio appears to be a simple inflammatory marker that indicates that the condition has become complicated, that is easily detectable and does not add additional cost.