  We address the question whether it is possible in GUTs to obtain R-parity
violation with a large ${\Delta L{/}\Delta B}$ hierarchy of strengths so that
the proton is stable while phenomenologically interesting $L$-violation is
present. We consider versions of SU(5) with a built-in Peccei-Quinn symmetry
spontaneously broken at an intermediate scale. The P-Q symmetry and the field
content guarantee a large suppression of the effective $B$-violating terms by a
factor $\Lambda^3_{PQ}/M_PM^2_X $ while the effective $L$-violating terms stay
large.
