Background: Leptin, a protein coded by the ob gene, is secreted by adipose tissue and controls body fat and hence body weight by reducing food intake and increasing thermogenesis. It is also thought to play a role in regulating reproduction through the hypothalamic-pituitary-gonadal (HPG) axis in mammals. The leptin protein has been localized in many reproductive tissues, including the ovary. Leptin may be a factor linking obesity and reproductive dysfunction and its deficiency or resistance can result in profound obesity, and infertility in females. In an effort to better elucidate the relationship between leptin and reproduction, we studied the status of serum leptin levels in female infertility.Methods: A case control study was carried out at Shifa College of Medicine/Shifa International Hospital, Islamabad. Serum leptin levels of 44 infertile females were compared with an age matched control group of 44 fertile females. Leptin levels were measured by DSL-10-23100 ACTIVE Human Leptin ELISA.Results: The results of the study revealed that both the BMI and serum leptin concentrations were significantly high in infertile women as compared to the fertile controls. Moreover, a strong positive correlation was found between BMI and leptin levels, with leptin levels increasing with an increase in body weight and BMI.Conclusion: The study suggests that obesity accompanied by hyperleptinemia is associated with fertility defect in females. However, further studies are required to determine the exact mechanism by which enhanced body mass and serum leptin concentrations lead to female infertility and its possible remediation.