A new alkaloid, stemoninine, obtained from the root of Stemona sessilifolia, and its stereochemistry have been elucidated by the analysis of the high resolution H-nmr spectrum; 1H, 1H-COSY; 13C, 1H-COSY shift correlated two-dimensional nmr spectra and 1H longrange shift; and 13C, 1H-COLOC-and nOe-correlated 2D-nmr techniques. © 1988, American Chemical Society. All rights reserved.