ABSTRACT Background: Resistin is an adipokine involved in developing obesity, insulin resistance, and comorbidities, such as type 2 diabetes mellites (T2DM). The present study aimed to estimate the circulating levels of Resistin mRNA and its plasma protein in patients with obesity in children vs adults and to correlate their levels with metabolic dysfunction parameters particularly, T2DM. Methods: This study included 80 subjects: 30 healthy subjects as the control group and 50 obese patients. The enrolled patients were classified into a pediatric group (n=25, age 8-18 years) and an adult group (n=25, age >18). Circulating resistin was measured by ELISA,and resistin mRNA was determined by real-time PCR. Results: Among the obese pediatric group, plasma resistin and its mRNA levels were significantly higher in the T2DM obese group( 15.4±1.26 and 2.51±0.31, respectively ) in comparison to other group ( 9.9±2.17, and 1.6±0.43, respectively), P <0 .001.Additionally, in the obese adult group, plasma resistin and its mRNA levels were significantly higher in the T2DM obese group (37.2±3.8and 6.54±0.56, respectively ) in comparison to other group ( 20.4±2.287, and 4.34±0.263, respectively ), P <0 .001. Interestingly, Age, BMI, FPG,2 HPP, FSI, HOMA-IR, HbA1c, and LDL values were significantly positively correlated with plasma resistin and its mRNA values. Conclusions: Plasma resistin and its mRNA were elevated in obese subjects, especially those with T2DM.In addition, plasma resistin and its mRNA values were significantly positively correlated with metabolic dysfunction parameters. Keywords: Obesity; Type 2 diabetes mellitus; resistin; children; Metabolic dysfunction.