Background. Legumes are a very important element of crop rotation, they have a high potential for protein production. Reducing weed infestation of these plants during the critical period of competition is essential for crop success, previous crop value and high seed yields. Evaluation of the competitive ability of legumes grown in Poland against weeds can be a valuable indication of which species to grow in conditions of increased weed infestation of fields, reduced doses of herbicides, unfavorable weather conditions, or systemic limitations of weed control technology. Material and methods. In a two-factor field experiment carried out in 2014–2015, the competitive ability of edible and fodder peas, yellow and white lupines and soybean against weeds was assessed. The reaction of these plants to chemical weed control and its lack was compared. Results. Abandonment of herbicide protection, compared to the application of a mixture of soil herbicides containing linuron and clomazone immediately after sowing, significantly increased the number and weight of weeds. Lack of weed control of selected legume plants resulted in a proven decrease in seed yield of: edible pea by 20%, fodder pea by 23%, yellow lupine by 32%, white lupine by 23% and soybean by 77%%. The yield of the tested legume plants was negatively correlated with the weight and number of weeds. Conclusion. The tested legume plants – edible pea, fodder pea, yellow lupine, white lupine and soybean – differed in their competitive ability against weeds. Soybean was the most sensitive to the presence of weeds, followed by yellow and white lupines, and the least sensitive were edible and fodder peas. In conditions of high weed infestation of fields and difficulties in keeping stands clean, the legume plant most recommended for cultivation is pea. Its cultivation allows obtaining seed yields of more than 3 Mg·ha-1, even in the absence of weed control.