Summary.Two trials comparing grass control by trifluralin and carbetamide in autumn‐sown legumes (Trifolium subterraneumL.,T. pratenseL.,T. repensL.,T. dubiumL. andLotus pedunculatusCav.) were conducted. Trifluralin was used pre‐sowing and carbetamide both pre‐sowing and post‐emergence.Both herbicides gave good control ofLolium perenneL. andPoa annuaL. at rates of 0·5 and 1·0 kg/ha a.i. for trifluralin and carbetamide respectively. Carbetamide showed no toxicity to any of the legumes up to 2·0 kg/ha except forLotus pedunculatusat that rate, whereas trifluralin was toxic to all species at 2·0 kg/ha. Neither herbicide controlled broad‐leaved weeds.The results are discussed in terms of the effects of soil fertility, plant age and maturity on the activity of these herbicides.La lutte contre les graminées adventices avec la trifluraline et le carbétamide dans les légumineuses