Some toxicity studies of warfarin (0.02% hydroxy coumarin) were carried against the albino norway rat, Rattus norvegicus and house mouse Mus muscufus. The gained results were concluded as follows: A—The Norway rat Hatters norvegricus: The warfarin bait consumption for each non choice and choice feeding test was 8.? gr and 4.5 gr for one day. The albino norway rat males were more palatabil (319%) to warfarin bait than females (31.9%). Warfarin gave 83.3% and 50% mortality for non choice and choice test. The average time to death was nearly equal for the obliged and free feeding test which was 5.7 day and 6 days for the albino norway rat. The reduction of rat body weight who objected to the warfarin bait was — 5.43 gm and 0.7 gm. For both tests non choice and choice feeding respectively: B-The house mouse Mus muscufus The house mouse males and females consumed 2.6 and 2.5 gmi'dayfrndividual and 1.8 and 1.9 gm/day'tindividual for warfarin bait under non choice and choice feeding system respectively. The palatabitity of house mouse was 45.1%. The warfarin bait gave 83.4% and 50% for non choice and choice feeding test. The results cleared that the body weight reduction it was ~2.6 gr and “2.5 gr. for both non choice and choice feeding system. The general average of time to death in both obliged and free tests were respectively 1.7 and 8.0 days.