The second-generation anticoagulants are currently used to control rodents all over the world.To investigate whether their use has resulted in development of resistance to bromadiolone in house rat (Rattus rattus) populations in India,standardized methodologies for feeding tests with anticoagulant bait and blood clotting response tests have been applied.The cereal based toxicity (LD50) of bromadiolone was subsequently estimated as 1.05 and 1.83 mg/kg for male and female rats,respectively.Rats (n =61) collected from five different poultry farms and treated with an LD50 and twice the LD50 dose,were tested for prothrombin time (PT) and International Normalized Ratio (INR) using a rabbit brain thromboplastin reagent and coagulometer.Only five male rats treated with an LD50 dose survived and these showed an increased PT from 14-18 seconds before treatment to 20-97 seconds at 48 hours after treatment.Their INR values increased from 0.697-1.016 before treatment to 1.016-5.453 at 48 hours after treatment.Tissue from these rats has been preserved for molecular characterization of the VKORC1 gene.Our study represents the first report of bromadiolone resistance in R.rattus populations from Punjab,India.