Methodology is suggested for calculation of effective elastic constants of layer containing intralaminar cracks. Trends are presented for layers with low and medium high crack densities, where the interaction between cracks can be neglected. The effective properties of the damaged layer are determined by back- calculation using previously developed GLOB-LOC model for thermo-mechanical properties of damaged laminate . It is shown that the effective transverse modulus and shear modulus of a layer decrease linearly with increasing crack density, whereas longitudinal modulus and major Poisson’s ratio do not change at all. Experimental data for multiple cracking are analyzed showing that linear approximation of crack density versus applied strain may have sufficient accuracy. These two linear trends are used to calculate the effective elastic properties of a layer as a function of strain.