  Motivated by the fact that the string scale can be many orders of magnitude
lower than the Planck mass, we investigate the required modifications in the
MSSM $\beta$--functions in order to achieve intermediate ($10^{10-13}$GeV)
scale unification, keeping the traditional logarithmic running of the gauge
couplings. We present examples of string unified models with the required extra
matter for such a unification while we also check whether other MSSM properties
(such as radiative symmetry breaking) are still applicable.
