The condensation of DNA induced by vinyl saccharide graft copolymers of N-methacryloy-lamino-D-glucose with N,N-dimethylaminoethyl methacrylate and N-vinylpyrrolidone with N-vinylamine and induced by the linear polycation poly(L-lysine) in solution, as well as the conformational changes of a DNA molecule during its interaction with polycations in solution, is studied by atomic-force microscopy, low-gradient viscometry, dynamic birefringence, spectrophotometry, circular dichroism, and electrophoresis. The differences in the conformational changes of DNA related to the effect of polycations and other agents inducing its condensation are discussed.