Annual fluctuation in seedfall and seedling dynamics of Fagus crenata was investigated over an 11 year period (1993-2003) at the Ohtakizawa Research Site, Shizukuishi, Iwate Prefecture, in order to examine the masting habit, pollination efficiency in relation to amount of flowering, pre-dispersal seed predator satiation by insects, and postdispersal generalist predator satiation. A great quantity of sound seeds (>94 m^-2) was produced in 1995, 2000 and 2003, while there were 5 years with no sound seeds. The proportion of sterile seeds did not significantly correlate with the number of staminate inflorescences. This tendency does not support the pollination efficiency hypothesis. The proportion of insect-damaged seeds by moth larvae, Pseudopammene fagivora, was negatively correlated with the number of fertilized seeds (sound seeds and insect-damaged seeds, etc.), and with the ratio of fertilized seeds in year N to those in year N-1. These tendencies support the predator satiation hypothesis at the pre-dispersal seed stage. On the other hand, there was no significant correlation between the number of sound seeds and the seedling emergence rate, or between the number of emerged seedlings and the seedling survival rate until the autumn of the same year. Such facts do not support the predator satiation hypothesis at the postdispersal stage. The failure to escape from postdispersal predators may be affected by the loose synchrony in annual seed production of co-occurring tree species (e.g., F. crenata, Aesculus turbinata and Quercus crispula) that share common predators (rodents).