The problems of phase transitions in commercial cellulose systems during processing are considered. The formation of structures in regenerated cellulose from viscose solutions during precipitation in different regenerated baths and in highly concentrated solutions of cellulose in N-methylmorpholin-N-oxide at different temperatures and shear deformations has been selected for this review. The difficulties in defining the type of structural ordering in these systems are demonstrated. Fractal analysis is used to study the structures. A close relationship between the characteristics of the structures and the fractal dimensions is elucidated. The prospects for the different methods of regulating structures in cellulose systems are discussed. (C) 2003 Wiley Periodicals, Inc.