From a mixture of bases from the epigeal part and the bulbs of Petilium raddeana (Rgl.) Vved. ex Pazij, a new base petisidinine has been isolated with mp 290-292°C (decomp.), composition C27H39NO3 (I). On the basis of the physicochemical properties of the alkaloid and a correlation with petisine, the structure and configuration of petisidinine have been established as those of 3β-hydroxy-20-(5-hydroxy-3-methylpyridin-6-yl)-5α-pregnan-6-one. © 1984 Plenum Publishing Corporation.