The author has investigated the effects of boiling with water and disintegration with alkaline solutions on the chemical composition and nutritive value of rice straw. The results are summarised as follows. 1) The starch value of the straw in dry matter was about 20%, which agrees with the result of Prof. T. KATAYAMA's experiments. 2) The boiling for 3 hours in water did not change the chemical composition and nutritive value of the straw. 3) When the straw was soaked in 0.25% sodium hydroxide solution for 4 hours, hardly any of its incrusting substances were removed, its digestibility was not promoted, and also the starch value, percent of dry matter, was nearly the same as that of the untreated straw. However when the straw was immersed 0.75 or 1.5% sodium hydroxide solution for 4 hours, or when it was boiled with the milk of lime(1% CaO) for 3 hours, a considerable quantity of the incrusting substances were extracted, the amount of digestible matter was much increased, and also its starch value became as much as thrice that of the untreated straw; actually it contained 53-58% of starch value in dry matter. 4) When the contents of the lignin and chlorine number decreased, the starch value of the treated straw increaced, but not proportionally. 5) The data obtained In dry matter percentages were as follows: [表] In conclusion the author expresses his best thanks to Prof Dr. T. KATAYAMA under whose guidance this investigation was made, and also Mr. S. AIHARA and Mr. J. YASUNAGA for their valuable assistance during the feeding experiments.