An expression is derived for the fracture energy, gamma, in brittle crystals, namely, gamma = kd(0)E, d(0) being the lattice spacing, E Young's modulus perpendicular to the fracture plane, and k is a constant. The value of gamma obtained through this expression is compared to experimental data for cubic crystals. Despite the fit, we conclude that because the fracture energy is dominated by the elastic constant, comparisons between a computed gamma and experimental data cannot be used to distinguish between bonding functions.