Maize (Zea mays) is one of the most important crops in the world, with nitrogen (N) fertilization being the most expensive input in its production. Based on a favorable variability, production costs can be reduced by the means of selection for nitrogen use efficiency (NUE). This study aims to analyze the variability in the collection of maize lines in terms of nitrogen use efficiency (NUE) and to identify the loci associated with the yield and grain moisture. The Agricultural Institute Osijek diversity panel comprises of 1,346 maize inbred lines genes with 56,000 SNP (Single Nucleotide Polymorphism) markers. The experiment was carried out with 109 selected inbreds, based on their performance in the long–term trials. The selected inbreds were testcrossed to a common tester from the Iodent heterotic group. The experiments in three nitrogen environments were carried out in 2023: N0 (no nitrogen fertilization), N69 (low nitrogen supply), and Nfull (sufficient nitrogen supply). Association mapping revealed varying associations between the SNPs and the yield/moisture under different nitrogen treatments, highlighting the influence of nitrogen stress on genetic mechanisms governing these traits. The research contributes valuable insights into maize adaptability to nitrogen levels, aiding in the development of strategies for stable and high–yield maize production.