The invention concerns quinazoline derivatives of Formula I ##STR00001## wherein R.sup.1 and R.sup.2 have any of the meanings defined in the description; processes for their preparation, pharmaceutical compositions containing them and their use in the manufacture of a medicament for use as an antiproliferative agent in the prevention or treatment of tumours which are sensitive to inhibition of erbB, particularly EGF, receptor tyrosine kinases.