The partitioning of the molecular electronic energy into true one-electron quantities defined by a molecular electronic virial theorem (MEVT) is studied for a number of molecules. Since the theorem is derived for exact wavefunctions, its applicability to various ab initio wavefunctions at difierent levels of accuracy is examined. The average percentage deviations of the theorem for near Hartree-Fock, double zeta, STO-6G and STO-3G type wave functions are 0.4, 1.7, 2.3 and 3.3, respectively.