A review of elementary-particle models based on low-energy supersymmetry is given. Supersymmetry is used in these models to compensate the quadratic divergence in the radiative correction to the mass of the Higgs boson in the Weinberg-Salam model and to solve the hierarchy problem in grand unification theories. The standard low-energy SU(3) $\otimes$ SU(2)L $\otimes$ U( 1) theory is replaced in this approach with the supersymmetric theory. A large number of new particles with masses Mw is predicted. The properties of these particles and possible experimental searches for them are discussed. Models based on different ways of supersymmetry breaking are considered. The central place is given to models with supersymmetry breaking due to supergravity, which have been particularly actively discussed in the last two years. Proton decay in supersymmetric GUT models is analyzed. Introductory ideas on supersymmetry, necessary for the understanding of most of this review, are presented in Section 1 and in the Appendix.