Аннотация:A review of close binary systems (CBSs) in the late stages of evolution is presented. High-mass andlow-mass CBSs are described separately: WR+OB systems, “quiet” X-ray binaries, massive transient X-raybinaries with Be stars, X-ray novae and bursters, cataclysmic and symbiotic binaries. Luminous blue variables(LBV objects) and radio pulsars in binary systems are discussed. Black holes in binary stellar systems, methods for their search, and black hole masses in X-ray binary systems are described. A number of specific systems are analyzed. The mass distribution of relativistic objects, WR stars, and their CO cores in binary systemsis described. The masses of stellar black holes and the possibility of testing the theories of gravity are discussed. Possible variations in the orbital periods of X-ray binaries due to enhanced quantum evaporation ofblack holes are presented.