Four of ten common varieties of cabbage tested at Ottawa from 1960 to 1963 were slightly or moderately resistant to Hylemya brassicae. Red Acre was the most resistant and Viking Golden Acre the most susceptible of the ten. Red Acre and Danish Ballhead were damaged less than Viking Golden Acre and harbored fewer maggots. Market Topper and Jersey Wakefield were also damaged less than Viking Golden Acre but harbored as many maggots. Resistance in Red Acre and Danish Ballhead was evidently due chiefly to low-attractiveness, and in Jersey Wakefield and Market Topper to tolerance. Differences in plant height and width, either between or within varieties, had little effect on the numbers of eggs laid on the plants. Of the Hylemya specimens identified, 99% of the eggs, 89% of the larvae, and 83% of the pupae were of H. brassicae and the remainder were of the H. liturata-platura complex.