The paper based on the researches carried out during 2006-2008 in the long term trial placed in 1990 on the preluvosoil from Oradea. Three kind of crop rotation (wheat – monocrop; wheat – maize; wheat – maize – soybean) were studied in unirrigated and irrigated conditions. The smallest content of the protein from wheat grains were registered in the wheat monocrop both nonirrigated and irrigated variant. In the wheat-maize and wheat-maize-soybean crop rotation the values registered were significant statistically bigger than in wheat monocrop. Irrigation determined the decrease of the protein content.