  Within supersymmetric SU(5) GUT we suggest mechanisms for suppression of
baryon number violating dimension five and six operators. The mechanism is
based on the idea of split multiplets (i.e. quarks and leptons are not coming
from a single GUT state) which is realized by an extension with additional
vector-like matter. The construction naturally avoids wrong asymptotic relation
$\hat{M}_D=\hat{M}_E$. Thus, the long standing problems of the minimal SUSY
SU(5) GUT can be resolved.
  In a particular example of flavor structure and with additional ${\cal
U}(1)\tm {\cal Z}_{3N}$ symmetry we demonstrate how the split multiplet
mechanism works out. Namely, the considered model is compatible with successful
gauge coupling unification and realistic fermion mass pattern. The nucleon
decay rates are relatively suppressed and can be well compatible with current
experimental bounds.
