This paper presents the fundamentals and the mathematical formulation to study desiccation cracking in soils based on Unsaturated Soil Mechanics as well as a numerical analysis of a previous desiccation test program. The numerical approach implemented in MATLAB is used in 2D simulations on radial sections of the cylindrical specimens and in a theoretical study of the stress field in plane strain conditions. The numerical analysis, based on two stress stare variables (total net stress and suction) is consistent and in good agreement with the experimental results, including the location of cracks and time of crack initiation.