Novel quinoxaline-di-N-oxide derivatives of the formula ##STR1## are disclosed, wherein R represents a hydrogen atom, an alkyl group of 1 to 12 carbon atoms, a cyanoalkyl group containing 1 to 4 carbon atoms in the alkyl moiety or an allyl group, andA represents a straight-chain or branched alkylene bridge member containing 1 to 4 carbon atoms.These compounds are useful for the control of pathogenic microorganisms and for stimulating the growth of domestic animals and productive livestock.