A range of interstellar electron spectra at energies between
100 MeV and 5 GeV has been derived from an analysis of the
observed galactic non-thermal radio spectrum and from consideration
of the existing uncertainties in the other relevant
physical parameters of the galaxy. We find that for energies
larger than ~ 300 MeV the electron spectrum is uncertain to a
factor of 4 due to uncertainties in the galactic magnetic field
strength and the total line-of-sight emission length. The uncertainty
in the electron spectrum increases towards lower
energies, exceeding a factor of 50 near 100 MeV, primarily due
to uncertainties in the galactic parameters affecting interstellar
radio absorption
