Novel 1-oxo-1,2-dihydroisoquinoline compounds of the formula ##STR1## wherein R.sub.1 represents a lower alkyl group or a phenyl lower alkyl group; R.sub.2 represents a lower alkyl group; R.sub.3 represents a hydrogen atom, a lower alkanoyl group, a lower alkyl group or a hydroxy lower alkyl group; and n is 0, 1 or 2 and the pharmacologically acceptable non-toxic salts thereof.The compounds of this invention are strong analgesic anti-inflammatory agents.