Introduction: Omentin, an adipokine, with anti-inflammatory effects reduces insulin resistance, and can hence, play an important role in prevention of cardiovascular disease and diabetes. The present study aimed to investigate the association of plasma and dietary fatty acids with gene expression of omentin in visceral and subcutaneous adipose tissues. Materials and Methods: Visceral and subcutaneous adipose tissues and fasting blood samples were obtained from 50 obese and 47 non-obese participants, who had undergone elective abdominal surgery. Dietary intakes were assessed using a food frequency questionnaire. Relative gene expression of omentin in visceral and subcutaneous adipose tissues was measured by Real-Time PCR and plasma fatty acids were measured using gas chromatography. Results: Omentin gene expression in visceral adipose tissue was higher in non-obese participants, compared to obese ones; however, no difference was found in subcutaneous adipose tissue. A significant direct association was observed between omentin gene expression in visceral adipose tissue with dietary monounsaturated fatty acid (MUFA) (P=0.011, β=0.394) in obese subjects and the plasma omega 6: omega 3 ratio (P=0.029, β=0.385) in non-obese subjects after adjustment for confounders. No association was observed between omentin gene expression in subcutaneous adipose tissue and plasma and dietary fatty acids. Conclusion: Dietary intakes of MUFA in obese participants and plasma omega 6: omega 3 ratio in non-obese ones were directly associated with omentin gene expression in visceral adipose tissue. Therefore, higher omentin gene expression by increasing dietary MUFA may be related to improvement of obesity and its associated comorbidities.