Disclosed are imidazonaphthyridine derivatives represented by formula (I) ##STR1## wherein: R.sup.1 represents lower alkyl or substituted or unsubstituted aryl; andX-Y-Z represents ##STR2## wherein R.sup.2 represents hydrogen, lower alkyl, alkenyl, aralkenyl, or --C (R.sup.5) H--(CH.sub.2).sub.n --R.sup.4 (wherein R.sup.4 represents substituted or unsubstituted aryl, substituted or unsubstituted pyridyl, substituted or unsubstituted furyl, hydroxy-substituted lower alkyl, lower alkanoyloxy, morpholino, lower alkanoyl, carboxy, lower alkoxycarbonyl, cycloalkyl, hydroxy, lower alkoxy, halogen or NR.sup.6 R.sup.7 wherein R.sup.6 and R.sup.7 independently represents hydrogen or lower alkyl; R.sup.5 represents hydrogen, lower alkyl, or phenyl; and n represents an integer of 0 to 3); and R.sup.3 represents hydrogen, mercapto, hydroxy, lower alkyl, or aryl and pharmaceutically acceptable sails thereof.The compounds show a potent anti-inflammatory, anti-allergic and broncho-dilative activity.