Abstract: The objective of this experiment was to know the viability of several forage crops of aged seeds. The period of the present experiment was long and it ranged around 50 days (45, 36, 55 days; nearly 1.5, 1 and 2 months, respectively, for 1983, 1991 and 1997 produced seeds) in the autumn of 2006. Except for two species of reed canarygrass (Phalaris arundinacea) and sorghum hybrid (Sorghum bicolor (L) Moench), the seeds produced in 1983 decayed above the level of (1/2 of seeds decay). Their tolerance of the seeds produced in 1991 to decay seemed to be strong as follows; reed canarygrass (Phalaris arundinacea) = Kentucky bluegrass (Poa pratensis)>sorghum hybrid (Sorghum bicolor)>white clover (Trifolium repense). In the seeds produced in 1997 white clover, one of leguminous forages, decayed at a level of (2/3 of seeds), so the leguminous species decayed more than all other gramineous species.