The effect of sterilization and incubation temperatures of fermented oak sawdust on Lentinula edodes hyphal growth was investigated. The pile of 33 tonnes of oak sawdust fermented in a plastic shed for 24 days. During the fermentation the acidity of the sawdust within the pile was lowered to pH 4.2 and temperatures increased to 58℃ in over 20cm depth. The sawdust samples collected at 20, 60, 80 and 100㎝ depth each and moistened to 65% water content were sterilized at 65, 100 and 121℃ each for an hour. The sterilized sawdust contained in 50㎖ test tubes was inoculated with L. edodes hyphae cultured on potato dextrose agar medium and then was incubated at 15, 20, 25℃ for four weeks. L. edodes hyphae grew faster, 94.6mm, on the sawdust collected from 60cm depth than other depths, and did at 25 incubation temperature after sterilization at 121℃. The hypahe grew only 9.9cm on the sawdust from 100cm depth. When the sawdust from 60cm depth was sterilized at 100℃, the hyphae grew best by 22.1cm at 15℃. However, on the sawdust sterilized at 65℃ the hyphae did not grow at all. Thus, we conclude that sawdust fermentation under 60㎝ depth and autoclaving it can improve L. edodes hyphal growth, but the sterilization of sawdust at 65℃ is not sufficient for the hyphal growth.