Research objective is improving the grain yield of wheat by reducing of winter and spring wheat cropsweedines. The studies were carried out on experimental fields of the Povolzsje Science Research Institute of selection and seeds production of P. N. Konstantinov. Volga region Scientifical-research Institute of Selection and Seed growing named after P. N. Konstantinov in 2012-2014. The main purpose of researches was to study influence of weeds for grain yield components in winter and spring wheat. The evaluation of the abundance of weeds was performed by the method of Drude. Under the influence of weed, productivity of land winter wheat decreased by 3-26%, spring wheat decreased by 17-33%. The most harmful for winter wheat turned out creeping-rooted weeds: Cirsium arvense, Convolvulus arvensis, of young weeds dominated Cánnabis ruderális, and wintering weed: Lactuca serriola, Thlaspi arvense. In the spring wheat was dominated weeds of creeping-rooted form: Convolvulus arvensis, Cirsium arvense, Sónchus arvénsis and Euphorbia virgata. Winter wheat is less exposed to weeds than spring wheat. Yield depression was mainly due to decrease the number of productive stems and dry wheat mass. Also on the harmfulness of weeds is influenced by the weather conditions of the year. For winter wheat during the wet and warm autumn dominated wintering weed: Thlaspi arvense, Lactuca serriola. In years with dry weather conditions creeping-rooted weeds prevail For spring wheat during the wet spring it is dominated the spring weeds in dry years the most harmful creeping-rooted weeds. For the harmfulness of weeds the density of the crop also affect. When sparse crops of weeds more harmful than at the optimum plant density. Infestation weeds adversely for the yield of both winter wheat and spring wheat.