Electric field gradients (efg's) at the different lattice sites of noncubic chalcopyrite-structure semiconductors were calculated by the first-principles method of Blaha and Schwarz and the results compared with PAC-measurements with the probe 111In(111Cd), 111mCd and 77Br(77Se). At the cation sites theory and expirements are in good accordance. With an empirical point change model the structure and temperature dependence of the efg's can be described very clearly.