A single-crystal of NH3 was grown in a thin-walled capillary at 178 K, and high-resoln. x-ray diffraction data were obtained for this compd. at 160 K to obtain information about electron d. distribution. Conventional and multipole refinements and deformation electron d. maps indicated small but significant N-H bond bending inside the NH3 tetrahedron that is in agreement with ab initio quantum-chem. calcns. and the VSEPR model. Topol. anal. of the exptl. charge d. distribution in the NH3 mol. was performed, and the data are compared with high-level quantum-chem. calcns. Crystals are cubic, space group P213, with a 5.1305(8) .ANG.; Z = 4, dc = 0.838. Some features of the intermol. H bonds in the crystal are discussed.