1-Substituted alkyl-2-oxo-hexahydroquinoxaline derivatives of the formula ##STR1## wherein A is lower alkylene; R.sub.1 is selected from the group consisting of alkyl, phenyl-lower alkyl, and substituted phenyl-lower alkyl; and R is selected from the group consisting of hydroxyl, halogen, lower alkanocyloxy, R.sub.4 -carbamoyloxy and arylthio, in which R.sub.4 is lower alkyl or aryl; and pharmaceutically acceptable salts thereof. The compounds are useful as agents for platelet aggregation inhibition, vasodilation and anti-lipoperoxide generation.