This paper presents time-dependent poroelastic failure analyses of boreholes drilled porous formations. The work is based on a recently derived analytical solution. The in directions inclined to the far-field stress principal axes in fluid-saturated isotropic analyses include collapse as well as fracturing failures. The time-dependent failures in relation to borehole inclination, azimuth, and mud pressure are presented. The critical roles of poroelastic constants in borehole stability are also demonstrated.