Abstract: The state of the art in the constitutive relations for unsaturated soils was summarized,including elastic models,Barcelona elastic-plastic model and its various modified forms,models using suction as stress variables,elastic-plastic models for expansive soils,damage models,thermo-mechanical models and models for wetting induced deformation.The problems related to the implementation of these models in the finite element analysis were also presented,including determination of suction and matrix formulation.