If a leptoquark is produced at HERA as a narrow resonance, various eff
ects tend to broaden the measurable mass distribution considerably. Th
ese effects are discussed here, with special emphasis on initial- and
final-state QCD radiation. A proper understanding is important to asse
ss the significance of data and to devise strategies for better mass r
econstruction. (C) 1997 Published by Elsevier Science B.V.