We investigated an effective method for the pretreatment of Japanese cedar for efficient enzymatic saccharification and ethanol production. A 45-atm steam explosion provided a comparatively large amount of glucose and reducing sugars. Addition of polyethylene glycol (PEG) influenced the digestibility of holocellulose in a 35-atm steam-exploded sample. However, we observed a negative effect on enzymatic saccharification when sodium hydroxide was used in the pretreatment. The maximum values of glucose and reducing sugars produced using consecutive pretreatments with a 25-atm steam explosion and an ionic liquid were 408 and 462 mg/ (g initial dry sample), respectively. The most positive effects on the enzymatic saccharification kinetics were observed when the above consecutive pretreatment methods were used. However, using the organosolv treatment of wood chips without the steam explosion is a more cost-effective pretreatment method for the enzymatic saccharification of Japanese cedar, and this results in 386 and 426 mg/ (g initial dry sample) of glucose and reducing sugars, respectively. (C) 2010, The Society for Biotechnology, Japan. All rights reserved.