The qualification of density of aphids population on winter triticale cultivated in different conditions of nitrogen fertilization was the aim of the work. Three winter triticale cultivars: Fidelio, Lamberto and Tornado, cultivated in natural field conditions at the Agricultural Experimental Station in Zawady (the Siedlce administrative district) with an application of the following levels the nitrogenous fertilization: 50, 100 and 150 kg ha-1, were used in the studies. The population as well as percentage of plants settled by two cereal aphids species: Sitobion avenae F. and Rhopalosiphum padi L. were determined in entomological observations. The results showed an increase of the population as well as percentage of plants settled by S. avenae along with an increase of the level of nitrogen fertilization on all studied winter triticale cultivars. In the case of R. padi, the considered dependence had a more complicated character, different for each studied cultivar and the levels of nitrogen fertilization. Moreover, it was ascertained that the level of applied fertilizers influenced the dynamics and structure of populations of both studied aphids species. The results of the study suggest that S. avenae reacted to the changes of the level of nitrogen fertilization more than R. padi.