Since the 1950s, anticoagulant rodenticides are used to control rodents in public health and agriculture sectors. The extensive use of these compounds has acted as selective force to rodents, leading to resistance. Resistance mechanisms have been identified in rats and mice, including the modification of the enzyme that activates vitamin K, vitamin K epoxide reductase (VKOR). Susceptibility levels of the Norway rat, Rattus norvegicus and the roof rat, Rattus rattus to coumatetralyl (first generation anticoagulant) and broamdiolone (second generation anticoagulant) by bioassay detection
method under laboratory conditions were studied. Animals were trapped from Greater Cairo, Egypt in which the anticoagulant rodenticides were used to control rodents for long periods. Complete mortality was recorded for both species and sexes within the standard feeding periods (under no-choice feeding test for 6-days to coumatetralyl and
4-days to bromadiolone). Rat species under studied still susceptible to coumatetralyl and bromadiolone. The present work revealed a significant correlation between species in comparison with consumed dose and death time. R. rattus showed more active ingredient intake (mg/kg) than R. norvegicus. Death time (days), R. rattus recorded higher mean values than R. norvegicus, also females showed higher mean values compared to males.