In this work, similarity and numerical solutions for some problems of unsteady heat transfer over different surfaces in the boundary layer of fluids through a porous medium are discussed. In these problems, we studied the influences of magnetic field, permeability of porous medium, heat generation / absorption, thermal conductivity, variable temperature. The governing equations are first cast into a dimensionless form by a nonsimilar transformation and the resulting equations are solved numerically by using the Runge-Kutta numerical integration, procedure in conjunction with shooting technique. The obtained results are shown in graphics and tabulated representation followed by a quantitative discussion. The main aim of this book which consists of four chapters, is to study similarity solutions of boundary layer of some fluid. In the following, a brief discussion of the chapters is given.