A glucoside of mangostin was synthesized and its structure has been determined as mangostin-3,6-di-O-glucoside on the basis of spectral and analytical data. A study of its pharmacology indicated it to have a cns depressant activity. The diglucoside also produced a significant rise in blood pressure.The rind of the fruit of Garcinia mangostana Linn. (Guttiferae) has been known to be astringent and has been used in the treatment of diarrhea and dysentry (1). Schmid was the first to isolate mangostin from the fruit hulls of this plant (2). The classical work on the structural elucidation of mangostin by Yates et al. (3) established that mangostin is the xanthone represented by structure 1. The recent review article by Hostetmann and Wagner (4) on the xanthone glycosides prompted us to prepare the glycoside of mangostin to study its pharmacological activity. Earlier, in connection with our study on the minor constituents of G. mangostana (5), we isolated a good quantity of mangostin. This paper reports the details of the synthesis of mangostin-3,6-di-O-glucoside and records some interesting pharmacological activity of this diglucoside.