The rheology of solutions of N-vinylpyrrolidone and methyl methacrylate copolymers in dimethylformamide in the temperature range 20–35°C was studied. The influence of temperature and of the molecular weight and composition of the copolymers on their interaction with the solvent was shown, expressed quantitatively in terms of intrinsic viscosity, the Huggins constant, and the mean square distance between the ends of the macromolecular chains.