  We study proton decay in a supersymmetric {\sf SO(10)} gauge theory in six
dimensions compactified on an orbifold. The dimension-5 proton decay operators
are forbidden by R-symmetry, whereas the dimension-6 operators are enhanced due
to the presence of KK towers. Three sequential quark-lepton families are
localised at the three orbifold fixed points, where {\sf SO(10)} is broken to
its three GUT subgroups. The physical quarks and leptons are mixtures of these
brane states and additional bulk zero modes. This leads to a characteristic
pattern of branching ratios in proton decay, in particular the suppression of
the $p\to \m^+K^0$ mode.
