The experiments on studying the injuriousness of wild oats (Avena fatua) summer early weed in crops of durum wheat were carried out in 2014-2016 on educational and experimental field of Omsk SAU located in the zone of southern forest-steppe of Omsk Region. The soil of the experi-mental plot was meadow and average power low humus medium loam chernozyom. Spring durum of Omsk Emerald variety was planted at the rate of norm 4.0 mln grains per hectare on 16 th -20 th of May. On allotments interplanted weevils of wild oats at the rate of 25, 50, 100 and 200 pieces of viable seeds per square meter. Other weed plants were removed manually during all vegetative period. The survival of both cultural and weed plants de-creased at the increase in number of the sowed via-ble seeds of wild oats. In the process of growth of density of a weed component also the mass of one weed and one cultural plant decreased. The contam-ination of agrophytocenosis increased from weak degree when subsowing 25 pieces/ m2 of wild oats (10.1 %) to average when subsowing 50 and 100 pieces/m2 (14.9-19.9 %) and strong when subsowing 200 pieces/ m2 (24.5 %). Thus even at weak degree of a contamination of loss of grain are essential. In percentage expression reduction of productivity of grain reached 11.6-17.2 - 21.5-29.7 % in compari-son with crops, pure from weeds. Losses of grain on one interplanted weevil of the weed made 14, 10, 6.5 and 4.5 kg/hectare (according to the growth of the quantity of weed plants on an allotment). Thus, the general injuriousness of wild oats in-creased in crops of durum wheat at the increase in its number and was expressed in productivity loss by culture from 35 to 90 g/m2, thus specific injuri-ousness on one weed plant decreased with 1.4 to 0.45 g of grain of wheat on 1 m2.