Bark of the New Caledonian monimiaceous plant Nemuaron vieillardii contains the alkaloids laurotetanine, N-methyllaurotetanine, norisocorydine, atheroline, O-methylflavinantine, and a new bisbenzylisoquinoline alkaloid nemuarine, which is the major alkaloid of the leaves. Nemuarine is shown to have a novel structure with a 5-6' ether link between the isoquinoline residues. © 1973, CSIRO. All rights reserved.