The first (ß) and second (y) electric dipole hyperpolarizabilities are calculated for the ground state of ammonia. All independent components of ßxßy and yxßyö are obtained from the energies of the molecule perturbed by a homogeneous electric field. The values of yxxxx, yxxxz, yxxzz and yzzzz are 1232, -106, 1077 and 4319 e4 a40Eh-3 respectively