To investigate the usefulness of adding perennial ryegrass to a mixture of orchardgrass/ladino clover, and to determine the optimum seeding rate of perennial ryegrass and the optimum cutting frequency in the sward of the mixture combined with perennial ryegrass, an experiment was carried out over a period of two years at Kangwon National University, Chunchon. Five different seed mixtures of orchadgrass (20 ㎏/㏊); ladino clover (3 ㎏/㏊) which were supplemented by 0 ㎏/㏊, 5 ㎏/㏊, 10 ㎏/㏊, 20 ㎏/㏊ and 30 ㎏/㏊ of perennial ryegrass, respectively, were sown in April 1972. Each of the seed mixtures was divided into two groups, 2-time cut group and 4-time cut group. The results obtained were summarized as follows: 1. In the first year, before the midsummer the botanical composition of perennial ryegrass marked 19.7∼29.3% in the 5 ㎏/㏊ of perennial ryegrass plot, 30.3∼35.8% in the 10 ㎏/㏊ plot, 41.5∼52.0% in the 20 ㎏/㏊ plot and 63.4∼71.1% in the 30 ㎏/㏊ plot but after the midsummer it lowered drastically to 0.0∼0.5%, 0.2∼7.8%, 0.2∼2.1% and 0.2∼2.3% respectively. It was considered that such a lowering of perennial ryegrass` ratio was caused by the numerous death of perennial ryegrass in the midsummer. 2. Most of the perennial ryegrass exsisted only during the first year. In the second year, perennial ryegrass disappeared entirely since the first cut in the 2-time cut group, and since the third cut in the 4-time cut group. 3. The increase of dry matter yield caused by the addition of perennial ryegrass was recognizable only at the first cut in the first year. 4. In the first year, the dry matter yield of the first cut in the 4-time cut group increased proportionally as the seeding rate of perennial ryegrass increased. The dry matter yields of the plots added more than 20 ㎏/㏊ of perennial ryegrass were significantly greater than that of the plot without perennial ryegrass (P$lt;0.05). 5. In the first year, since the third cut the dry matter yield in the 4-time cut group decreased in proportion as the seeding rate of perennial ryegrass was raised. 6. The annual dry matter yields of the 4-time cut group in the first year, the plots contained perennial ryegrass, marking 8.49∼9.07 t/㏊, showed smaller yield in comparison with the plot without perennial ryegrass which produced 10.13 t/㏊. 7. The effect of seeding rate of perennial ryegrass on the second year`s dry matter yield and botanical composition was not found. 8. The annual dry matter yield of the 4-time cut group was smaller by 0.30 t/㏊ than that of the 2-time cut group in the first year but the former was larger by 2.59 t/㏊ than that of the latter in the second year. 9. Generally the botanical composition ratio of perennial ryegrass and ladino clover was higher and that of orchardgrass was lower in the, 4-time cut group than in the 2-time cut group. 10. The 2-time cut group recorded far more dead material with 1.42∼1.99 t/㏊ than the 4-time cut group which presented 0.42∼0.72 t/㏊.