Berberis laurina Billb. is a canmm shrub in the Rio de la Plata region and in south Brazil. From the leaves we have been able to isolate berberine, (-)-tetrahydropalmatine and protopine. In the trunk bark and root, there are at least six alkaloids of which we have isolated four: berberine, previously reported (2,3), and three bisbenzylisoquinoline bases: obaberine (O-methyloxyacanthine) (4) (see Table I) and two new alkaloids. One of these from the evidence which follows is a diastereomer (absolute configuration -+ (5)) of O-methylthalicberine (++)(5), and we have named it O-methylisothalicberine (I); the other we have called lauberine (IIIa).