  This paper addresses the role of Large Extra Dimensions in some flavor
changing neutral current (FCNC) driven processes. In particular we have
investigated radiative decays of charged leptons within models with only one
universal extra dimension (UED). Loop contributions with internal fermions and
scalars of comparable mass would seem to yield sizeable amplitudes, since the
generic quadratic suppression factor is changed into a linear one. Such
scenarios can in principle be realized in models with universal extra space
dimensions. Yet our calculations of the Kaluza-Klein (KK) contributions to
these radiative decays show this expected relative enhancement to disappear due
to the near mass degeneracy of the heavy neutrinos from the different
generations. In this paper we estimate also the UED contribution to the
$B_{s,d}\to\gamma\gamma$ rate and find an enhancement of 3% and 6%,
respectively, over the SM prediction.
