Control of the botanical composition of a sward heavily infested with tufted hair grass (Deschampsia caespitosa L. (P. Beauv.)). A trial was established at a site of an altitude of 1,300 m on grassland within the area of Nizke Tatry National Park (NAPANT) in 1997 and research was conducted over 1998-2000. Changes in the botanical composition were investigated after mechanical treatment of the sward, followed by drilling and sowing a grass-clover mixture. The sward was utilised by 2 cuts and the botanical composition was determined by the method of projective dominance before cuts. Mechanical and biological interventions influenced significantly the composition of phytocoenosis. A proportion of D. caespitosa decreased from 56% in the original sward to 8-18% in the third experimental year. Consequently, there were changes in the proportions of botanical groups, and diversity of valued forage species increased. From the viewpoint of feeding value, characteristics of the treated swards ranged from less valuable to semi-cultural ones. Efficiency of the sward improvement techniques used during research was satisfactory. Treatment 1 (rotary tilling of whole surface area prior to sowing, broadcasting) was found to be the most efficient in terms of the botanical composition changes of the sward and its feeding value. However, a long-term effect of the treatments may be expected only if adequate grassland management practices are applied