The Rheology of polymer solutions is divided into four chapters: concepts and basic concepts of rheology, the viscosity of diluted polymer solutions, the viscosity of the concentrated solutions of polymer and the viscoelastic properties of polymer solutions. Chapter one includes the basic concepts of rheology. Chapter 2 includes subsections: theories on the viscosity of diluted polymer solutions, factors influencing the rheological behavior of the diluted solutions, the influence of the molar mass and polymer polydispersity the viscosity, the effect of shear on the viscosity of diluted polymer solutions and relations viscosity - temperature of the diluted polymer solutions. Chapter 3 includes subsections: theories on the viscosity of concentrated solutions of the polymers, the conformation of the polymer in the solution concentrated, viscosity dependence of the molar mass of the polymer, the influence of the nature of solvents and the temperature dependence of the viscosity of the concentrated solutions.