The paper provides information about experimental research on consequences of increased nitrogen deposition to the ecosystem of alpine meadows in Jalovecká dolina (Western Tatra Mts., Slovakia). In this ILTER site we established 25 experimental permanent plots in 2002. The experiment consists of three treatments with addition of nitrogen (20, 60, and 150 kg.ha–1.year–1), one treatment with addition of phosphorus (50 kg.ha–1.year–1), and a control treatment. The site is equipped with a complex climatic station, rain gauge, collector for wet deposition measurements, microlysimeters and resin bags (later replaced by ion exchange discs). The results indicate saturation of the ecosystem by nitrogen and limitation of the primary production by phosphorus. They also suggest that a long legacy of acid deposition in the Western Tatra Mts. had already resulted in a depletion of both base cations and soluble aluminium, and an increase in extractable iron concentrations. In conjunction with this, we observed a nitrogen deposition-induced reduction in the biomass of vascular plants. In the paper we discuss also consequences of the experiment to species composition and abundance of vascular plants and epigeic invertebrates, as well as the role of the microbial communities in the nitrogen cycle and decomposition.