The aerial parts of Halfordia kendack (Rutaceae) have yielded the known alkaloid trans-erioaustralasine ([rel]-1-acetoxymethyl-4.8'-epoxy-3-(1'beta,2'beta-epoxy-3'beta,4'alpha-para-menthyl-3'-yl)quinolin-2-one) together with four new alkaloids. The latter were characterised by spectroscopic methods as trans-deacetoxyerioaustralasine ([rel]-1-methyl-4.8'-epoxy-3-(1'beta,2'beta-epoxy-3'beta,4'alpha-para-menthyl-3'-yl)quinolin-2-one), trans-deacetoxyerioaustralasine hydrate ([rel]-1-methyl-4.8'-epoxy-3-(1'alpha,2'alpha-dihydroxy-3'beta,4'alpha-para-;menthyl-3'-yl)quinolin-2-one), trans-erioaustralasine hydrate ([rel]-1-acetoxymethyl-4.8'-epoxy-3-(1'alpha,2'alpha-dihydroxy-3'beta,4'alpha-para-menthyl-3'-yl)quinolin-2-one) and trans-1-epi-deacetoxyerioaustralasine hydrate ([rel]-1-acetoxymethyl-4.8'-epoxy-3-(1'beta,2'alpha-dihydroxy-3'beta,4'alpha-para-menthyl-3'-yl)quinolin-2-one).