A brief review of the evolution of theoretical concepts of the character of physical quantities anomalous behaviour near second order phase transitions in systems with defects is provided. For defects of the “local phase transition temperature” type the range of applicability of the “imperfect scaling” theory is shown to be absent at all. In the case of extremely small defect concentrations the scaling regime inherent in a system absolutely free of defects may exist and thereafter, as the phase transition temperature is approached, the system switches to the strong binding regime which has not been studied yet. For noticeable concentration of the defects the system transforms to the strong binding regime within the range of applicability of the mean-field approximation. The self-consistent procedures of taking account of defects within the framework of the mean-field theory in the region preceding that of the strong-binding regime are described in detail.