Abstract: From Sarcococca ruscifolia, the mixed crystal of sarcorucinine A and A1 were ob-tained, but was very difficulty in separating. The structure of sarcorucinine A was determined by X-ray analysis for the mixed crystal. Compounds 3 and 4 were isolated from the reduction of mixed crystal with LiAlH4, and their structures were elucidated on the basis of the interpre-tation of MS, IR, 1H, and 13C NMR spectra. Thus, the structrue of sarcorucinine A, could be deduced as A'△^16 3a-dimethylamino-20α-methylmethylamido-pregnene (2), and was further comfired by FAB-MS / MS spectra. The structure of the sarcorucinine B was deduced by us-ing the same spectroscopic analysis. The present paper deals with the application of FAB-MS / MS technique in structural elucidation of sarcorucinine A, A　 and structural elucidation of sarcorucinine B.

Key words: Sarcococca ruscifolia, Pachysandra alkaloid