. 2015. Influence of genotypic mixtures on field pea yield and competitive ability. Can. J. Plant Sci. 95: 315Á324. Field pea breeding programs have been very successful at improving plant and disease resistance; however, limited success has been achieved in improving the competitive ability of field pea. A study was conducted to determine whether growing field pea in two-way genotypic mixtures could improve the crop's yield and competitive ability. A second objective was to determine if genetic relatedness had any effect on the mixing ability of genotypes. Genotypes were chosen on the basis of pedigree and included two sister lines (CDC1987-3 and CDC1897-14), their common parent (Eclipse), and a distantly related genotype (Midas). The four genotypes were grown as pure stands and as all possible two-way mixtures in field experiments conducted at Lethbridge and St. Albert, Alberta, from 2010 to 2011. The results revealed that CDC1897-3 )Eclipse suppressed the model weed (barley); it reduced seed production by 47% (442 kg ha(1 ) and 61% (391 kg ha (1 ) compared with the same components within pure stands at Lethbridge 2010 and Lethbridge 2011, respectively. The same mixture also reduced model weed (barley) biomass production by 61% (831 kg ha Bien que les me´langes illustrent la possibilite´d'une plus grande compe´titivite´du pois, les re´sultats n'e´taient pas cohe´rents d'un site-anne´e a`l'autre. Malgre´tout, quelques-uns accroissent le rendement et la compe´titivite´de la culture comparativement aux ge´notypes peu compe´titifs en peuplements purs.