The invention relates to quinazoline derivatives of the formula: ##STR1## �wherein: Y.sup.1 represents --O--, --S--, --CH.sub.2 --, --SO--, --SO.sub.2 --, --NR.sup.5 CO--, --CONR.sup.6 -, --SO.sub.2 NR.sup.7 -, --NR.sup.8 SO.sub.2 -- or --NR.sup.9 - (wherein R.sup.5, R.sup.6, R.sup.7, R.sup.8 and R.sup.9 each independently represents hydrogen, alkyl or alkoxyalkyl);R.sup.1 represents hydrogen, hydroxy, halogeno, nitro, trifluoromethyl, cyano, alkyl, alkoxy, alkylthio, amino or alkylamino.R.sup.2 represents hydrogen, hydroxy, halogeno, alkyl, alkoxy, trifluoromethyl, cyano, amino or nitro;m is an integer from 1 to 5;R.sup.3 represents hydroxy, halogeno, alkyl, alkoxy, alkanoyloxy, trifluoromethyl, cyano, amino or nitro;R.sup.4 represents a group which is or which contains an optionally substituted pyridone, phenyl or aromatic heterocyclic group! and salts thereof; processes for their preparation and pharmaceutical compositions containing a compound of formula I or a pharmaceutically acceptable salt thereof as active ingredient. The compounds of formula I and the pharmaceutically acceptable salts thereof inhibit the effects of VEGF, a property of value in the treatment of a number of disease states including cancer and rheumatoid arthritis.