This experiment was canied out to study the effects of seeding and harvesting dates on the growth of early and late maturing rye(Seca1e cereale L.) varieties at the forage testing field of S.N.U., Suweon, from September 1986 to May 1989. Leaf and tiller numbers of rye per plant were increased with earlier seeding date, but no difference in the tiller numbers was found between harvesting dates of early and late maturing rye varieties. Tiller dry weight of an early maturing rye veriety, Wintermore was higher than that of a late maturing rye variety, Kodiak when sown as early as September. Maximun leaf area index(LA1) and leaf area index duration(LA1D) were achieved with earlier seeding and early maturing rye varieties. A higher correlation between the maximum LA1 or LAID and dry matter accumulation of rye varieties was observed in this experiment.