The invention relates to the use of cinnoline derivatives of formula (I) ##STR1## wherein Z represents --O--, --NH--, --S-- or --CH.sub.2 --; m is a n integer from 1 to 5; R.sup.1 represents hydrogen, hydroxy, halogeno, nitro, cyano, trifluoromethyl, Cp.sub.1-3 alkyl, C.sub.1-3 alkoxy, C.sub.1-3 alkylthio or NR.sup.6 R.sup.7 (wherein R.sup.6 and R.sup.7, which may be the same or different, each represents hydrogen or C.sub.1-3 alkyl); R.sup.2 represents hydrogen, hydroxy, auoro, chioro, methoxy, amino or nitro; R.sup.3 represents hydroxy, halogeno, C.sub.1-3 alkyl, C.sub.1-3 alkoxy, C.sub.1-3 alkanoyloxy, trifluoromethyl, cyano, amino or nitro; R.sup.4 represents hydrogen, hydroxy, halogeno, cyano, nitro, amino, trifluoromethyl, C.sub.1-3 alkyl or a group R.sup.5 --X.sup.1 (wherein X.sup.1 represents --O--, --CH.sub.2 --, --S--, --SO--, --SO.sub.2 --, --NR.sup.8 CO--, --CONR.sup.9 --, --SO.sub.2 NR.sup.10 --, --NR.sup.11 SO.sub.2 -- or NR.sub.12 -- (wherein R.sup.8, R.sup.9, R.sup.10, R.sup.11 and R.sup.12 each independently represents hydrogen, C.sub.1-3 alkyl or C.sub.1-3 alkoxy C.sub.2-3 alkyl) and R.sup.5 is an optionally substituted alkyl, carbocylic or heterocylic group which may be saturated or unsaturated and may be directly linked to the cinnoline ring or be linked via a carbon chain which may have heteroatom linking groups within it and salts thereof, in the manufacture of a medicament for use in the production of an anti angiogenic and/or vascular permeability reducing effect in a warmn-blooded animal such as a human being, processes for the preparation of such derivatives, pharmnaceutical compositions containing a compound of formula (I) or a pharmnaceutically acceptable salt thereof as active ingredient and compounds of formula (I). 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.