Background & Aim: Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health. This study investigated the influence of thymol on obesity, liver enzymes and adipose tissue in mice fed a high fat diet (HFD). Experimental: Male NMRI mice were divided into two groups; the control group that given normal rodent diet and obese group that received HFD for 8 weeks. The obese animals were divided into 3 groups: one group received thymol orally (12 mg/kg body weight) for a period of 56 days. Obese group didn't receive any treatment and the sham groups received thymol (12 mg/kg body weight) dissolved in grape seed oil. Alteration in body weight gain and serum biochemical markers were assessed and fat tissue was fixed in formalin in order to prepare microscopic slides. Finally, body weight, liver enzymes (ALT and AST), TNF-α‚ adiponectin‚ total antioxidant (TAC) and leptin levels were measured in obese mice compared with control mice. Results: Thymol treatment resulted in increased serum adiponectin and TAC level, while significantly reduced TNF-α level (P<0.05). The leptin level decreased in HFD mice, but it was not significant (P>0.05). Serum ALT and AST levels were significantly decreased (P<0.05) in HFD mice, compare with control. The diameter of adipose cells were decreased in thymol-supplementation mice (P<0.001). This combination does not lead to significant reduction in body weight, but it can help to prevent weight gain. Recommended applications/industries: The thymol was able to prevent HFD induced obesity in mice and attenuation of inflammation markers. پرونده مقاله