Changing climate conditions can be critical for the vitality of trees, as high temperatures and/or drought may cause inadequate nutrition of trees in parallel with a worsening of crown condition. It is crucial to account for nutrient limitation when studying the forest response to climate change (Jonard et al. 2015). Nutrient contents of tree foliage, which reflect atmospheric and soil-related influences, are an important part of UNECE ICP Forests monitoring programme (Krüger et al. 2020). The main goals of this study were to: (I) investigate the influence of climate conditions on mineral nutrition of common beech, and (II) determine if concentrations of N, P, K, Ca and Mg in common beech foliage differ between tree defoliation classes. Stratified sampling of trees based on their defoliation class (≤25%, >25%) was performed on 28 Level I beech plots (10 in Dinaric, 18 in Pannonian biogeographical region) in 2018, 2019 and 2020, five trees per plot and defoliation class. We detected significant nutritional differences between trees of different defoliation classes for P and Mg, but only in certain years – for less defoliated trees P was higher in 2019, and Mg was lower in 2018. The ratios of N/P, Ca/Mg, K/Ca, K/Mg and K/Ca+Mg were higher for less defoliated trees in most cases. All ratios with Ca (N/Ca, K/Ca, K/Ca+Mg) were higher for less defoliated trees in 2018 and 2019, but not in the drier 2020. Calcium concentrations increased with increasing soil pH (CaCl2) for plots in the Pannonian region, which has a wider span of pH values, while in Dinaric plots with pH mostly higher than 5 such correlation was not found. A multitude of climate factors correlated with nutrient concentrations, but summer temperatures seem to have the strongest negative influence.