Microwave heating of a multilayered system has wide applications in thawing, drying, hyperthermia treatment, and many more. A typical multilayered system can be viewed as a combination of low and high dielectric materials. The propagation of microwaves within a multilayered system can be represented either by exponential Lambert's law or by an exact solution of Maxwell's equation. The exact solution for microwave propagation is based on both the transmitted and reflected waves, whereas Lambert's law is based purely on transmission. Lambert's law is a good approximation for a semi-infinite sample,and the validity of Lambert's law for a multilayered assembly is limited to orientation of various dielectrics. Two specific cases for a multilayered sample are considered, and the detailed scattering effects during microwave propagation have been analyzed via Lambert's law and the exact solution.