Legumes play an important role in organic farming, as they enable farmers to reduce the use of nitrogen fertilizer. In an eleven years plot experiment in Lithuania, legumes were the most variable part of the fl oristic component. Their variation was usually cyclic and depended on diff erent factors. Composition of herbage phytocenoses varied depending on their biological properties and ability to adjust to meteorological conditions. Legumes amount in the sward varied from 13.2 to 43.6%. They spread best (34.4–43.6%) when summer was rainy. The spread of legumes in herbage is also aff ected by mineral fertilisers. Having fertilised the sward with P60K60 and having calculated the relationship between legumes and fertilisers used it was found that phosphorus fertilisers had a greater eff ect on the spread of white clover. A medium strong correlation (r = 0.52) was determined between these indicators. Grasses occupied from 32 % to 63.1 % of the sward area. With sward senescence the content of forbs (mainly Taraxacum offi cinale L.) increased. Dry matter yield varied within 2.3–5.1 t ha-1 range. It was determined by legumes. The eff ect of legumes on herbage dry matter yield was very strong (r = 0.786**l), and that of grasses moderate (r = 0.619*l).