AC Emerson, a medium-early maturing oilseed flax (Linum usitatissimum L.), was released by Agriculture and Agri-Food Canada, Agri-Food Diversification Research Centre, Morden, Manitoba, in 1994. The cultivar has high oil quality, medium-large seed size and was high yielding in both early and late seeding tests in the Black and the Brown Soil zones of Manitoba and Saskatchewan. Because of its chlorosis tolerance, it is particularly well suited to the calcareous soils of Manitoba. It is immune to North American races of rust caused by Melampsora lini and moderately resistant to wilt caused by Fusarium oxysporum f. sp. lini. Key words: Flax, oilseed, Linum usitatissimum L., cultivar description