  We study flavour violation in the minimal SUSY SU(5) GUT assuming all the
third generation Yukawa couplings to be due to the renormalizable physics above
GUT scale. At large $\tan\beta,$ as suggested by Yukawa unification in SU(5),
sizable flavour violation in the left (right) slepton (down squark) sector is
induced due to renormalization effects of down type Yukawa couplings between
GUT and Planck scales in addition to the flavour violation in the right slepton
sector. The new flavour physics contribution to $K-\bar K,$ $B-\bar B$ mixing
is small but might be of phenomenological interest in the case of $b\to
s\gamma.$ The sign of the latter contribution is the same as the sign of the
dominant chargino contribution, thus making the constraints on SUSY scale
coming from $b\to s\gamma$ somewhat more restrictive. The most important
feature of the considered scenario is the large rate of lepton flavour
violation. Given the present experimental constraints, the $\mu\to e\gamma$ and
$\mu-e$ conversion branching ratios are above the sensitivity of the planned
experiments unless the SUSY scale is pushed above one TeV.
