Abstract. Effects of sport tourism were examined in dry grassland stands with fix sample plots in four sites of strictly protected areas of Buda Mountains and Pilis in Duna-Ipoly National Park in the vicinity of Budapest (Hungary). The size of all sample plots was 2×2 m in all sites, we designated 4×10 sampling quadrats and 4×10 control quadrats. The date of surveying was in May and July in 2013. The sampling sites were exposed to different type of illegal sport activities. The questions we tried to answer were which changes were caused by different sport activities, is the nature protection work in the surveyed areas effective enough. Data of sample and control plots were analyzed by multivariate analyses. The species composition of parallel plots of samples and controls were compared with their ecological parameters. According to the results of cluster analysis and redundancy analysis, the composition of species of the sample plots deviated from the control plots and the difference between them were at Pilis site the most considerable. In the sample plots the rate of uncovered soil surface was meaningful and the stony surface and the leaf litter cover were higher there than in the control plots. At the sample plots the distribution of social behaviour categories showed higher ratio in the categories of generalists, ruderal competitors and weeds, while the ratio in the categories of natural competitors and specialists decreased there. At the sample plots the life forms categories showed higher ratio in the categories of therophytes and chamaephytes than at the control plots.