The experiment reported here was conducted at Suweon and Sunghwan. to evaluate desirable agronomic characteristics, forage yield and quality of nine introduced oat (Avena sativa L.) cultivars in comparison with the control cultivar Cayuse during the fall and spring seasons for three years. Speed oat and G-sprinter showed earlier in maturity than the control cultivar Cayuse, but Taiho, Zenshin and Almighty were recorded as late types. Taiho, Hay oat and Swallow tended to more lodging than the control cultivar under rainy growing conditions and Taiho, Zenshin and Hay oat were more susceptible to barley yellow dwarf virus among the cultivars tested. At Suweon, the early type cultivars Speed oat and G-sprinter significantly outyielded the control cultivar Cayuse over the 3 years of the fall experiment, but no significant forage yield was found between the early type cultivars and the control in the spring experiment except for 1991 At Sunghwan, the early type Speed oat and late types Almighty and Zenshin significantly outyielded the control in the fall experiment of 1991, but the 3 years of experiment showed no significant difference in the forage yield of oat cultivars in the spring experiment. Over the 3 years of the fall and spring experiments at both Suweon and Sunghwan. the crude protein (CP) content and in vitro dry matter digestibility (IVDMD) of the early types Speed oat and G-sprinter were lower than those of the control and late types, but the acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents of the early types Speed oat and G-sprinter were slightly higher than those of the control and late types. Results of this experiment indicate that the early type oat cultivars tended to higher forage yield than the late types when sown in the fall, but no cultivar differences in dry matter yield were found when sown in the spring.