AbstractThe biochemical mechanisms of warfarin resistance in the house mouse (Mus musculusL.) have not been fully investigated. In some populations of warfarin‐resistant mice there is a reduction in sensitivity of hepatic vitamin K‐epoxide reductase to inhibition by warfarin. This is similar to a proposed mechanism of anticoagulant resistance in the Norway rat (Rattus norvegicusBerk.). The same enzyme in other warfarin‐resistant populations is, however, sensitive to warfarin inhibition. Other studies have indicated that detoxification may play a role in conferring warfarin resistance in house