A comparison of the farming value oi the three grasses (orchard grass, timothy grass and Italian ryegrass) cultivated in pure stands and in mixtures with red clover was made during,the years 1990 -1993. The experiment was carried out on a medium brown alluvial soil at Brzesko-Okocim, Italian ryegrass was the strongest limiting factor of the dynamic red clover growth, especially in the first year of the experiment, while timothy grass was the weakest limiting factor. During three veal's the grass/clover mixtures gave the dry matter yields similiar to the yields of grasses in monoculture cultivation which were fertilized every year at 150 kg N/ha rate. However, taking into account the crude protein yield, mixtures exceeded the grasses in pure stands about 30-40%. In the fourth year of utilisation the mixtures gave the lower yields as a result of clover lessening in the sward. Therefore, to ensure the yields similiar to the previous years, the mixtures demanded fertilizer N at 50-60 kg/ha. From simplified calculation it was clear, that the grass cultivation in pure stands which required nitrogen fertilization was 2.5-3 times more expensive than the grass/clover mixture cultivation. From the analyzed grasses, Italian ryegrass showed the lowest production potential in pure sowing as well as in grass/clover mixtures.