In this chapter, a new failure criterion for the transversely isotropic rocks is presented. The new criterion is based on two distinct failure modes; one is the sliding mode where the failure is caused by sliding along the discontinuity, and the other is the non-sliding mode where the failure is controlled by the rock material and is not dependent on discontinuity. This failure criterion is defined with seven material parameters. The physical meanings of, and the procedures for determining, these parameters are described. Both the original Jaeger criterion and the extended Jaeger criterion are shown to be special cases of the proposed criterion. The accuracy and applicability of the proposed failure criterion are examined using the published experimental data. The data used cover various types of transversely isotropic rocks, different orientation angels and confining pressures. The predicted strength behaviors of the transversely isotropic rocks agree well with the experimental data from various investigators. The accuracy and applicability of the proposed empirical failure criterion are demonstrated in this paper.