The alkaloid composition of leaves of Lupinus linearis Desr. (3 ecotypes) and L. gibertianus Smith (6 ecotypes) from A rgentina and Brazil were studied by capillary gas-liquid chrom atography and GLC-mass spectrometry (EI-M S). Both species are closely related according to morphological criteria. This view is supported by the alkaloid profiles which are very similar and share a series of new and uncom mon alkaloids. Main alkaloids are lupanine, 13-hydroxylupanine, esters of 13-hydroxylupanine (e.g. 13-angeloyloxylupanine, 13-tigloyloxylupanine, 13-benzoyloxylupanine, 13-ci5/frans-cinnamoyloxylupanine). Minor alkaloids are: sparteine, 1 1, 1 2 -dehydrosparteine, am m odendrine, tetrahydrorhom bifoline, angustifoline, a-isolupanine, 5, 6-dehydrolupanine, 11, 12-dehydrolupanine, N-formylangustifoline, 13-ds-cinnamoyloxymultiflorine. New m inor alkaloids which have been tentatively identified by GLC-MS are 13-hydroxy-17-oxolupanine and corresponding esters (13-angeloyloxy-17-oxolupanine, 13-tigloyloxy-17-oxolupanine, 13-benzoyloxy-17-oxolupanine, 13-cis-cinnamoyloxy-17-oxolupanine, and 13-fran.s--cinnamoyloxy-17-oxolupanine). © 1993, Walter de Gruyter. All rights reserved.