The experiment was conducted during the period 1982-1987 at the field station Sredec, Stara Zagora region on leached Smolnitza soil. Two maize hybrids (300 and 700 FAO) grown under irrigation and five levels of Nitrogen (0, 302, 242, 182, 121 kg N ha�1) and Phosphorus fertilization (0, 65, 52, 39, 26 kg P ha�1) were observed. Plant samples were taken for measuring the dry biomass and the content of total Nitrogen after an interval of 14 days from germination. On the basis of these indexes the uptake of Nitrogen was determined. During the vegetation period some meteorological parameters which have an influence on maize grown and the content and uptake of Nitrogen were measured daily (at 7, 14 and 21 h). Regression equations describing the relations between temperature sum, precipitation sum, saturation deficit sum and the uptake of Nitrogen for each level of Nitrogen and Phosphorus fertilization were drawn up. A parallel between the requirements of the two hybrids with the meteorological elements during the vegetation period was carried out. It was established that meteorological conditions have a different influence on the uptake of Nitrogen by maize. This depends more on the level of fertilization than on the hybrids.