Yu.E.Kuzovlev Dynamical virial relations and invalidity of the Boltzmann kinetic equation (51K, LaTeX2e revtex4-1) ABSTRACT. A sequence of exact relations is found which connect one- and many-particle time-dependent distribution functions of non-equilibrium low-density gas with their derivatives in respect to mean density. It is shown that, at least in the context of spatially non-uniform gas evolutions, these relations forbid the ``molecular chaos propagation'' and imply inapplicability of the Boltzmann kinetic equation even under the Boltzmann-Grad limit and regardless of degree of the non-uniformity. Statistical and physical meaning of this result is explained.