The liver plays a major role in lipid metabolism, importing free fatty acids and manufacturing, storing, and exporting lipids; derangements in any of these processes can lead to the development of non-alcoholic fatty liver disease (NAFLD). Fatty acid synthase (FAS) is a key enzyme in de novo lipogenesis and circulating FAS is a biomarker of metabolically demanding human diseases. In this investigation, we aimed to evaluate circulating FAS in NAFLD patients and correlate its level to serum lipid parameters. The study included forty NAFLD patients and forty age and sex- matched healthy subjects as controls. The results of the study revealed that FAS levels were significantly higher in NAFLD patients compared to their level in the controls (P < 0.0001). Additionally, a positive correlation was found between the levels of FAS and BMI (r = 0.57), and between FAS levels andtriglycerides and low density lipoprotein cholesterol levels in NAFLD patients (r = 0.79 &0.53, respectively). In conclusion, elevated levels of circulating FAS can be considered as a biomarker of fatty liver disease.