The structures of Kr and Xe single crystals were detd. by x-ray diffraction at low temps. Both noble gases were crystd. by in situ crystn. techniques and found in a fcc. type structure. The electron d. was reconstructed in both crystals from the x-ray structure amplitudes. It was calcd. by full-potential LAPW method at the exptl. geometry. A topol. electron d. anal. and the deformation electron d. maps showed that both Kr and Xe atoms are contracted in the solid state relative to the free atoms and are slightly aspherically polarized to each other, with bridges directed along atom-atom lines. The crit. point characteristics indicate the closed-shell interactions in both crystals.