In the geometric optics approximation for inhomogeneous, nonstationary, anisotropic and dispersive media a generalized Leontovich parabolic equation and the equation of energy conservation are deduced. These equations are sensitive to the form of constitutive equations and the orderings of the field variables and medium parameters. The paper deals with the general theory of wave packets in inhomogeneous, nonstationary, anisotropic and dispersive media. Considering the second order geometric optics approximation, we generalize the Leontovich parabolic equation  and obtain the equation of energy conservation. It has been shown that the final forms for these equations differ for different orderings of the field variables and medium parameters and depend upon how we consider the inhomogeneity and nonstationarity in the constitutive equation. © 1980 IOP Publishing Ltd.