A review of experimental data concerning physical properties of globular protein at mild denatured conditions shows that at the present time about 20th proteins were obtained in the "molten globule" state at mild denatured conditions (acid or basic pH, high temperature or moderate concentrations of guanidine hydrochloride or urea). This state is nearly as compact as the native state and has a well pronounced secondary structure but has no rigid tertiary structure. A possible role of the molten globule state in the processes of formation and of degradation of globular proteins are discussed.