Osmoconditioning and hardening effects for the seed germination of normal and naturally aged rice seeds were studied through analyzing the total sugars and alpha-amylase activity. The normal seeds which used to have high germination rate accelerated germination with the osmoconditioning at the suboptimal temperature of 17 degrees. On the other hand, the aged seeds did not affect germination rate at 25 degrees, while increased germination rate and accelerated germination a little at 17 degrees. Hardening of aged seeds increased germination rate by 10~15% compared with control seeds at both 17 and 25 degrees and accelerated germination. Total sugar content and alpha-amylase activity of normal seeds were higher than did aged seeds. The aged seeds with treatment of osmoconditioning and hardening increased total sugar content and alpha-amylase activity, but hardening was more effective than osmoconditioning. The alpha-amylase activity was positively correlated with the total sugar content and germination rate.