The stress distribution around a strongly oblate spheroidal cavity in a cubic crystal is determined by the equivalent inclusion method. The stress concentration factor is shown to be a product of two factors: one factor is purely geometric; the other factor depends on the material properties. By allowing the aspect ratio of the cavity to approach zero, the stress intensity factor of the associated penny-shaped crack is deduced. The energy release rates of cracks on {100} planes are computed for different growth directions. Theses results are found to be correlated well with Zener’s anisotropy factor.