Plasma line observations obtained from incoherent radar backscatter have been used as a ground-based method for deriving information about the size and anisotropy of the ionospheric photoelectron fluxes. In the past, data interpretation has been confined to altitudes above the F2 peak. Measurements below the F2 peak consistently show an anisotropy in the ratio of the downshifted to upshifted amplitudes of 20--50% when it is generally assumed that diffusion processes dominate. We describe calculations of the plasma line intensity which use a multiangle multienergy calculation of the photoelectron distribution function. The calculated electron flux exhibits a small low-altitude low-energy anisotropy which is reflected in the plasma line measurements. Given anisotropic elastic electron-neutral cross sections, the flux anisotropy arises when the local mean free path is of the order of the local scale height. The net effect is conversion of a spatial density inhomogeneity into a velocity distribution anisotropy.