We have calculatedab initiothe three-dimensional potential-energy surface of the NH2molecule at 145 nuclear geometries spanning energy ranges of about 18 000 cm-1for the NH stretch and 12 000 cm-1for the bend. Theab initioconfiguration-interaction calculations were done using the multireference MRD-CI method. The calculated equilibrium configuration has NH bond lengthre= 1·0207 Å and bond angle α = 103·1°. The rotational-vibrational energies for14NH2,14NHD and14ND2were calculated variationally using the Morse-oscillator rigid-bender internal-dynamics Hamiltonian. For14NH2we calculate that υ1= 3267 (3219) cm-1, υ2= 1462 (1497) cm-1and υ3= 3283 (3301) cm-1, where experimental values are given in parentheses.