Schistosomiasis is one of the most widespread parasitic diseases in the world. During the past decade numerous schistosomiasis control projects in many developing countries have shown that control of snail vectors by molluscicides can be a rapid and efficient means of reducing or eliminating the transmission of this disease.1} Molluscicides of plant origin are currently receiving considerable attention in the hope that these toxins will be harmless to nontarget organisms and will be rapidly biodegraded.2)In the course of our screening for naturally occurring molluscicides,3 ~5) we found that the crude methanol extract of fresh leaves from the East African medicinal plant Calpurnia aurea (Papilionaceae)6>7) possesses molluscicidal activity against the South American snail Biompholaria glabratus. Two quinolizine alkaloids were isolated from this extract, and identified by spectroscopic methods. We now describe the isolation, activity and structure elucidation of these alkaloids. An analysis of proton-proton connectivities by high resolution GOSY experiments is also reported.