The in virto dry matter digestibility of barley straw increased as increasing concentration alkali. Digestibilities were higher with 100℃ for 1 hour treatment than 23℃ for 24 hour treatment. The most effetive alkali on a weight basis in increasing in vitro dry matter digestibility of barley straw was NaOH followed by NaOH+KOH (50 : 50) and KOH, respectively. However, on a molar basis, treatment with NaOH and KOH were comparable. The reduction of cell wall was highest with NaOH followed by NaOH+KOH (50 : 50) and KOH, respectively. Acid detergent fiber cellulose and lignin contents were not changed by alkali treatment. However, gross energy of alkali treated straw was lower than untreated. barley straw. A combination of NaOH and KOH treatment did not enhance higher digestibility over NaOH treatment alone. Thus, the lack of achievement of full potential digestibility of NaOH treated straw does not appear to be due to a Na and K imbalance.