The U.S. Department of Agriculture World Collection of Flax Germ Plasm was screened for resistance to 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine). A single plant selection of CI 719 was the most resistant. It produced dry matter equaling 33% of the control in soil treated with atrazine at 1 lb/A while Arny produced 10%. In another experiment, the selection of CI 719 produced 44% as compared to only 11% for Koto. The atrazine-resistant selection was not resistant to 2-chloro-4,6-bis(ethylamino)-s-triazine [simazine]. Seed of this selection of CI 719 have been entered in the World Collection and assigned the number CI 2484.