Nonalcoholic fatty liver disease (NAFLD) is a spectrum of liver disorders ranging from simple fat accumulation in the hepatocytes (hepatic steatosis), to liver inflammation and hepatocytes injury (nonalcoholic steatohepatitis, NASH) with increasing levels of fibrosis to cirrhosis and hepatocellular carcinoma (HCC). So, the current study aimed to determine the role of circulating zonulin in NAFLD and to correlate its level with biochemical parameters, IL-6 and liver histopathology. The study included 56 adults subjects with proved NAFLD by ultrasonography and liver biopsy, as well as 20 healthy subjects were enrolled in the study as a control group. For patients and controls the following were done: Clinical examination, abdominal ultrasonography, routine laboratory investigations, body mass index (BMI) and the homeostasis model assessment of insulin resistance (HOMA-IR) were calculated, the circulating zonulin and IL-6 were measured. The results of the study: HOMA-IR, IL-6 and serum zonulin were significantly increased in NAFLD group compared to controls. Additionally, in NASH group, a significant increase in HOMA-IR and serum zonulin was detected as compared to group of simple steatosis. The serum zonulin level was positively correlated with HOMA-IR, liver histopathology and serum IL-6. In conclusion: The increasing serum levels of zonulin in patients with NAFLD and further increase in NASH group denoting its possible role in NAFLD progression. Future large scale studies are recommended to use this novel marker in early detection of NAFLD and to prevent disease progression.