The possibility of annual and perennial legume crops to be used for undersowing of degraded pasture stands and alfalfa seed production stands was studied in the conditions of the Northern Bulgaria. The direct undersowing of degraded pasture stands was done after harvest with these legumes: birdsfoot trefoil (Lotus corniculatus L.), red clover (Trifoliumpratense L.), black medick (Medicago lupulina L.), arrowleaf clover (Trifolium vesiculosum Savi), and common vetch (Vicia sativa L.). The undersowing of degraded seed production stands of alfalfa was done in autumn of the fourth year of using with subterranean clover (Tr. subterraneum ssp. brachycalicinum cv. Antas). Red clover showed the best results in terms of suitability for the direct undersowing of degraded pasture stands. Subterranean clover could be used for the direct undersowing of the degraded alfalfa seed production stands due to its self-seeding ability.