Background: Spontaneous bacterial peritonitis (SBP), a life-threatening infection in patients with advanced liver cirrhosis, is traditionally diagnosed by a high white blood cell count (polymorphonuclear leukocyte count (PMN) > 250/μL) in ascitic fluid. However, this method can be slow. Objective: This study explores ascitic fluid calprotectin as a potentially faster and more accurate diagnostic tool.Patients and Methods: Ninety patients with decompensated liver cirrhosis (45 with confirmed SBP and 45 without SBP) were included. Ascitic fluid calprotectin levels were measured in all participants. Results: SBP patients had significantly higher calprotectin levels than the non-SBP group. Additionally, calprotectin levels correlated with white blood cell counts and other inflammatory markers in the ascitic fluid. Using a cut-off value of 433.7 ng/ml, calprotectin achieved a sensitivity of 73.3% and a specificity of 85.1% for detecting SBP. Conclusion: Ascitic fluid calprotectin shows promise as a reliable and potentially faster method for diagnosing SBP in patients with cirrhosis. It could serve as a valuable addition to existing diagnostic tools.