Holocelluloses have been prepared in substantially quantitative yields from extractive-free straws of wheat, oats, barley, rye, and flax by acid chlorite treatments. Estimation of the pentosan, uronic acid anhydride, Cross and Bevan cellulose, and acetyl contents of the recovered holocelluloses showed that little loss of carbohydrate material had occurred during isolation. Lignin contents of the holocelluloses from the various straws varied between 2.5 and 3.5%. Extension of the chlorite treatments beyond the number required to isolate the holocellulose resulted in only minor diminution of lignin but caused considerable loss of carbohydrate material. Mild delignifying treatments of crude holocellulose with hypochlorite (acid and neutral), hypochlorite and sulphite extraction, bromine, and alcoholic ethanolamine had effects similar to those of acid chlorite. The major portion of protein in the straws was removed by acid chlorite. The isolated holocellulose contained more ash than the original straws.