This field experiment was undertaken to assess the effects of cutting frequency (3,4,5,6 times) and N rate (1,15,30,40 ㎏/l0a) on the yield and persistence of different forage species within a mixed grass/clover sward. 1. Under frequent cutting, dry matter yields of grasses were usually reduced at all of the rates of N, whereas yields of legumes generally increased except at a cutting frequency of 6 at the low rate of N. Weeds increased at high rate of N and reduced at the low rates. Total yield was highest with 4 cuttings. 2. By increasing the N rate, yields of grasses, weeds and the total yield were increased at all cutting frequencies, whereas yields of legumes were reduced. N fertilizer had a greater effect on grass yield than on weeds, so the percentage of weeds in the sward was reduced as a result of fertilizing with N. 3. Optimum cutting frequency and N rate were correlated with each other. Grass and total yields were highest with 4 cuttings and 30 N, legume was highest with 5 cuttings and O N, and weeds was highest with 5 cuttings and 40 N. Generally, infrequent cutting and high rate of N had negative effects on clover and weeds. 4. At the low rate of N, yields of grass and weeds, and total yield were highest with infrequent cuttings. At the high rate of N, the yield of legume was highest with frequent cuttings. 5. Yields of grass, legume and weeds in mixed sward were differentially influenced by cutting and N fertilizer (main effects and interaction = P $lt; 0.01).