Heterocyclic amidines with anti-inflammatory and analgesic activity that inhibit nitrogen oxide production, of formula (I): ##STR00001## in which: G.sub.1 and G.sub.2 are hydrogen, halogen, hydroxyl, C.sub.1-C.sub.4 alkoxy, C.sub.1-C.sub.4 alkyl, and an amidino substituent of formula Q, provided that, for each compound of formula (I), only one of the two substituents G.sub.1 or G.sub.2 is an amidino substituent of formula Q: ##STR00002## and in which the substituents W, Y and X are combined to form 9- or 10-membered bicyclic heteroaromatic derivatives containing up to 2 hetero atoms in the same ring; and Z is an aryl or heteroaryl group, a linear or branched C.sub.1-C.sub.6 alkyl or alkenyl chain, a C.sub.1-C.sub.4 alkyl-aryl group or a C.sub.1-C.sub.4 alkyl-heteroaryl group.