Background: When an ascitic fluid is infected with bacteria, it's known as spontaneous bacterial peritonitis (SBP). Polymorphonuclear leukocyte (PMN) count of at least 250 cells/mm³ is required for diagnosis of SBP despite the positive results of bacterial culture in the ascitic fluid. The number of PMNs in the ascitic fluid is counted after bringing it to the laboratory. True-negative results can be produced by the lysis of PMNs in the laboratory. The operator is responsible for manually counting the PMN in the ascitic fluid, which can cause a delay in the diagnosis. Proteins that bind iron, such as lactoferrin, are detected in both human mucosal secretions and PMN-specific granules. Lactoferrin concentration in faeces has been shown to be very sensitive and specific for the identification of intestinal inflammation in previous research. Objective: Diagnosis of spontaneous bacterial peritonitis could be improved by using ascitic fluid lactoferrin. Methods: PubMed, Google scholar and Science direct were searched using the following keywords: Ascitic fluid lactoferrin, spontaneous bacterial peritonitis and polymorphonuclear leukocytes. The authors also screened references from the relevant literature, including all the identified studies and reviews, only the most recent or complete study was included. Conclusion: A biomarker for the existence of PMNs and the detection of SBP in cirrhotic individuals would be lactoferrin in the ascitic fluid.