This study was designed to investigate the correlation between obesity and antibiotics. The obesity was induced by high fat diet (corn oil diet) for 8 weeks. 60 male albino rats were divided into obese group (30 rats), and another non-obese group (30 rats), which subdivided into three groups. Group I (N=10) Control, Group II: (N=10) non obese-rats were received vancomycin 30mg/kg BW for 7days and Group III: (N=10) rats were received doxyrubicin 0.6mg/kg BW for 3 successive weeks and some rats were decapitated after each injection. Group IV (N=10) control obese. Group V (N=10) obese rats were received vancomycin with the same dose as in non obese group. Group VI (N=10) obese rats were received the same dose as in non-obese group. Body weight, leptin, lipid profile, lipid %, blood glucose, malondialdhyde and (HOMA-IR) hemostasis model assessment insulin resistance in the obese group injected I/P with vancomycin HOMA-IR in comparison to control group was increased. The level of serum leptin, insulin concentration in the obese group injected I/P with vancomycin was decreased, while the expression level of ob gene increased which investigate leptin resistance. Thus, the present study suggested relationship between antibiotics and obesity.