Resistance of 27 varieties of Oilseed rape (Brassicae napus L.) and Sinapis arvensis to cabbage aphid (Brevicoryne brassicae L.) was evaluated in field and growth room conditions.In field experiments,varieties were evaluated by "Infestation Index" which was a criterion of comparing resistance of varieties was calculated with "mean infested stem lenght" cross to "percentage of infested plants".Comparing of data from field treatments showed that varieties of Hyola 308,Hyola 401,Eurol,PF, and Okapi didnot significantly different with resistant control,Sinapis arvensis,which was the most resistant variety in field.Under controled conditions,antixenosis and tolerance of 27 varieties of oilseed rape were studied in two sets of experiments.In the first and second experiments,each test plant were infested by 10 and 5 aphids,respectively.In both expriments of antixenosis and first tolerance there were no significant differences between varieties.However,in second experiment of tolerance(5 aphid per ,there were significant diffrences between varieties.Three varieties showed tolerance effect which two of them were already resistance in field,Eurol and Okapi.These two varieties and PF with Boomrang,the most sensitive varieties ,were used in antibiosis experiments.In this experiments ,parameters such as intrinsic rate of nachral increase(rm) and Mean relative growth rate(MRGR),pre-reproductive period and reproductive rate were measured.Results indicated that in growth room and field conditions,variety boomrang was the most sensitive to cabbage aphid and three varieties of Eurol,Okapi and pf were the most resistant in both experiments in field and growth room conditions.