Electronic Journal of Differential Equations, Vol. 2002(2002), No. 24, pp. 1-17. Title: Existence and uniqueness of classical solutions to certain nonlinear integro-differential Fokker-Planck type equations Authors: Denis R. Akhmetov (Sobolev Inst. of Math., Novosibirsk, Russia) Mikhail M. Lavrentiev, Jr. (Sobolev Inst. of Math., Novosibirsk, Russia) Renato Spigler (Univ. di Roma Tre, Italy) Abstract: A nonlinear Fokker-Planck type ultraparabolic integro-differential equation is studied. It arises from the statistical description of the dynamical behavior of populations of infinitely many (nonlinearly coupled) random oscillators subject to ``mean-field'' interaction. A regularized parabolic equation with bounded coefficients is first considered, where a small spatial diffusion is incorporated in the model equation and the unbounded coefficients of the original equation are replaced by a special ``bounding" function. Estimates, uniform in the regularization parameters, allow passing to the limit, which identifies a classical solution to the original problem. Existence and uniqueness of classical solutions are then established in a special class of functions decaying in the velocity variable. Submitted October 23, 2001. Published February 27, 2002. Math Subject Classifications: 35K20, 35K60, 45K05. Key Words: nonlinear integro-differential parabolic equations; ultraparabolic equations; Fokker-Planck equation; degenerate parabolic equations; regularization.