  An analysis is given of the decay $\mu \to e+ \gamma$ in an MSSM extension
with a vectorlike generation. Here mixing with the mirrors allows the
possibility of this decay. The analysis is done at the one loop level with the
exchange of charginos and neutralinos and of sleptons and mirror sleptons in
the loops. A one loop analysis with W and Z boson exchange and mirror leptons
and neutrinos is also considered. The effects of CP violating phases from the
new sector on the decay $\mu\to e \gamma$ are analyzed in detail. The
constraints arising from the current upper limit on the branching ratio
${\cal{B}}(\mu\to {e} \gamma)$ from the MEG experiment of $2.4\times 10^{-12}$
(at 90\% CL) on the parameter space of SUSY models and on vectorlike models are
explored. Further, the MEG experiment is likely to improve the upper limit by
an order of magnitude in the coming years. The improved limits will allow one
to probe a much larger domain of the parameter space of the extended models.
