Piumerinine, a novel lupin alkaloid has been isolated from the stem of Plumeria rubra and assigned structure 1 on the basis of spectral studies. This constitutes the first example of the occurrence of bicyclic lupin alkaloids in subfamily Plumerioideae of the Apocyanaceae.p-Plumeria rubra (Apocyanaceae) commonly grows as ornamental plant in Southeast Asia particlllarly in Pakistan and India. It is reputed to possess purgative, diuretic, abortificient, antituberculotic properties, and is also used as remedy for rheumatism, diarrhoea, blennorrhes, gonorrhoea, syphilis, veneral sores, and leprosy. 1.2Enormous work3-' have been done on various parts of this plant, but no alkaloid has ever been isolated or characterised, although their presence has been reported in 1951 by Douglas and Kiang. 7 Herein we report the isolation and structural elucidation of a novel lupin alkaloid plumerinine from the freshly collected and shade dried stems. The structure 1 has been assigned to it on the basis of extensive spectral studies.