In advanced ovarian cancer, the main goal of surgery is complete debulking with no visible residual tumor, and predicting it before surgery has become a goal that still unresolved. The ability in advanced ovarian cancer surgery varied between healthcare facilities. Recent discovery put forward the role of fatty acid as one of the main source of energy for ovarian cancer aggresiveness and the role of fatty acid binding protein (FABP) escpecially FABP4 expression as an important biomarker for predicting residual disease in ovarian cancer. There are no data about FABP4 serum in ovarian cancer and it's role in predicting the extensiveness of advanced stage ovarian cancer. To evaluate correlation between FABP4 serum level with PIV Fagotti Score and Peritoneal Carcinomatosis Index (PCI) in advanced stage ovarian cancer. Analytic observational study. Among 28 subjects, most age groups (46.4%) are 40–45 years of age, 46.4% with normal body mass index, 71.4% with ovarian cancer stage IIIC, 75% with high grade serous adenocarcinoma, average ascites volume 3232.1 ± 2006.9 mL, median CA125 serum 1094 u/mL (12–19425 u/mL). The rate of optimal and complete debulking is 53.5% from 28 subjects. Strong expression of FABP4 on 42.9% subjects. MeanFABP serum 69.6 ± 51.4 ng/mL. Mean PCI score is 14.5 (3–29), mean PIV score is 6 (2–12). There is a significant correlation between FABP4 expression and FABP4 serum level (p<0.05) with moderate power (r=0.55), and a significant correlation with moderate power (r=0.421) between FABP4 serum level with PCI and PIV score. There is a significant correlation with moderate power between rising FABP4 serum and the extent of peritoneal carcinomatosis evaluated by PCI and PIV Fagotti Score in advanced stage ovarian cancer.