The famous Russian scientist Corresponding Member of Russian Academy of Sciences David Abramovich Kirzhnits passed away after long and serious illness on May 4, 1998. D.A.Kirzhnits was born on October 13, 1926 in Moscow. Having graduated Moscow University he was working at 1950 - 1954 as an engineer on munition factory in Gorky (N.Novgorod). Since 1954 all his life was connected with the Theoretical Department of P.N.Lebedev Physical Institute of Russian Academy of Sciences to work where he was invited by the Nobel Prize winner I.E.Tamm. Here D.A.Kirzhnits has done all his famous scientific works and taught a number of pupils. The scientific heritage of D.A.Kirzhnits is bright and profound. At the end of 1940 he has started the investigation of the Fermi - Thomas model and he carried this interest through his whole life. These classical works by D.A. Kirzhnits belong to 15 most cited papers devoted to the equation of state of matter. D.A.Kirzhnits has undertaken the nontrivial efforts to overcome well known problems of the nonlocal field theory. One of the world-known results of this work was the development of the new direction in quantum field theory which is known as the method of differentiation over the coupling constant. This method was successfully applied to the quantum theory of a few interacting particles. In the beginning of the 70's D.A. Kirzhnits invented the theory of cosmological phase transitions in particle theories with spontaneous symmetry breaking. This theory has radically changed our views on the physical processes in the early universe. In particular, this theory is the basis of inflationary cosmology and of the theory of cosmic strings. In 1978 D.A. Kirzhnits and A.D. Linde were awarded the M.V. Lomonosov Prize of the Academy of Sciences of the USSR for these studies. After discovery of high - temperature superconductivity D.A.Kirzhnits has suggested a novel possibility that the static dielectric function can have the negative sign, which allowed to remove a number of restrictions on the transition temperature. In the last years D.A.Kirzhnits has done a number of important works concerning energy losses of high energy particles in matter, and superfluidity of matter in neutron stars. D.A.Kirzhnits had an exceptionally kind and intelligent personality to his friends and colleagues, but he was implacable to any attempts to step aside science ethics. His family, friends, colleagues and the whole physics community shall miss him dearly.