An analytic solution has been derived to predict the dispersion of pollutants in homogeneous, isotropic and saturated porous media. In order to define the dispersion phenomenon, the coefficients of longitudinal and transverse dispersion must be determined. Relationships for the two coefficients under specific boundary conditions are presented. Since the variables characterizing the properties of fluid, porous medium, and tracer influence the dispersion of a pollutant, two dimensionless parameters, namely, the inverse Schmidt number and the molecular Peclet number, were obtained. Using these parameters, the experimental data on longitudinal and transverse dispersion were compiled and analyzed over a wide range of the flow velocity, grain size, and molecular diffusion of tracer.