  Motivated by the recent HERA events which are consistent with a possible
leptoquark interpretation, we discuss the prospects for including additional
light colour triplets and anti-triplets in the spectrum of supersymmetric
unified theories. We focus on a particular string-inspired Pati-Salam model,
and propose a simple mechanism by which a light colour triplet of charge -1/3
plus anti-triplet of charge 1/3, may have a mass of order 200 GeV, with one of
the new states having leptoquark couplings and with proton decay suppressed. We
also discuss possible scenarios for gauge unification in such a model.
