Rock masses in nature contain numerous discontinuities as cracks, joints, cleavages, beddings and even faults etc. In the cracked material, the stress intensity factors (SIFs) at crack tips, which govern the crack propagation and are associated with the strength of the material, are strongly affected by crack inclination angle, orientation of anisotropy. This book presents the development of a unified numerical framework based on the BEM for modeling crack propagation behavior in anisotropic rocks. The following topics are discussed in this book: 1. Evaluating the SIFs i iA new formulation of the BEM, based on the relative displacements at the crack tip, is used to determine the mixed mode SIFs of isotropic and anisotropic rocks. 2. Determination of Fracture Toughness i iA procedure to determine the fracture toughness of anisotropic rocks under mixed mode I-II loadings is presented. 3. Simulation of Crack Propagation i iThe BEM formulation combined with the maximum circumferential stress criterion was used to simulate the crack propagation paths.