Abstract. In this work we study the well-posedness of the Cauchy problem for a class of pseudo-differential parabolic equations in the framework of Weyl-Hörmander calculus. We establish regularity estimates, existence and uniqueness in the scale of Sobolev spaces H(m, g) adapted to the corresponding Hörmander classes. Some examples are included for fractional parabolic equations and degenerate parabolic equations.Mathematics Subject Classification. Primary 35L80; Secondary 47G30, 35L40, 35A27.