ABSTRACT The problem of diffraction of SH-waves by two coplanar Griffith cracks situated at the interface of two different orthotropic media has been analyzed. Fourier transform and integral equation method have been used to solve this problem. The expressions for the stress intensity factors (SIFs) around the crack tips are obtained. Numerical values of SIF and the crack opening displacement for several orthotropic materials have been calculated and plotted graphically to show the effect of material orthotropy.