In this study, the crystallinity index and crystallite size of cotton linters used as raw material were found to be 59.6% and 6.1 nm, respectively. While the crystallinity index and crystallite size in unbleached soda pulp were determined as 63.0-63.4% and 5.4-5.6 nm., respectively, the same data in bleached soda pulps were found to be 63.2-68.0% and 7.6 nm. On the other hand, the crystallinity index in cellulose of unbleached organosolv pulp decreased from 75.8% to 66.9%, and its crystallite size did not change with bleaching. Although the crystalline structure in the unit cell of cellulose of unbleached soda pulp was dominantly monoclinic (Ibeta), this structure in unbleached ethanol pulp was found to represent triclinic (Ialpha) and monoclinic (Ibeta) phases. With bleaching, the crystalline structure of soda pulps was not changed, although this structure in some organosolv pulps changed.