Aim and background: Spontaneous bacterial peritonitis (SBP) is an infection of the ascetic fluid that occurs in the setting of decompensated liver cirrhosis. Ascetic fluid PMN count 250 per cubic mm or above is the gold standard for it's diagnosis. The aim of this work was to assess the serum ascetic vitamin D gradient (SADG) in the setting of SBP. Methods: This cross-sectional case control analytic study was carried out on 50 patients diagnosed with portal hypertensive ascites who was categorized into two equal groups: Group I: cirrhotic ascetic patients with SBP and Group II: cirrhotic ascetic patients without SBP. Results: There was a significant positive correlation between SADG and ascetic PNM count and serum vitamin D in group I and between SADG and ascetic and serum vitamin D in group II. SADG can be used to discriminate between group I and group II at a cutoff level of < 0.55, with 72% sensitivity, 76% specificity, 75% PPV and 73.1% NPV. Ascetic fluid glucose and lactate dehydrogenase was statistically significantly higher in group II when compared with group I (P