In agriculture, weeds tend to compete with the crop for scarce resources like water, light and nutrients, which incurs losses to farmers. Consequently, farmers must deal with weeds to derive maximum benefits for their crops and the environment. The aim of this paper was to assess the competitiveness of common bean crops in the presence of hairy beggarsticks (Bidens pilosa) at different population densities. The treatments were arranged in replacement series using five proportions (0:16, 4:12, 8:8, 12:4 and 16:0) of common bean and hairy beggarsticks in a fully randomized design, with four replicates. The analyzed variables were dry mass of the aerial part and height of plants. Competitive analysis was performed using diagrams applied to substitute experiments and indices of competitiveness. With regard to the two evaluated variables, the common bean was more resourceful than the hairy hairy beggarsticks. Key words: Replacement series, competition, shoot dry mass, stature, Bidens pilosa, beans.