Quantitative descriptions of flow and transport in subsurface environments are often hampered by uncertainty in the input parameters. Treating such parameters as random fields represents a useful tool for dealing with uncertainty. We review the state of the art of stochastic description of hydrogeology with an emphasis on statistically inhomogeneous (nonstationary) models. Our focus is on composite media models that allow one to estimate uncertainties both in geometrical structure of geological media consisting of various materials and in physical properties of these materials.