A new isoquinoline alkaloid, cohirsitinine, has been isolated from Cocculus hirsutus. Its structure has been assigned as 1 on the basis of spectral studies. Its relative stereochemistry has been determined by homonuclear 2D ¹H-nmr (COSY-45, J-resolved, NOESY) and nOe difference measurements. Cocculus hirsutus L. Diels (Menispermaceae), locally known as "jamati-kibel," is a climbing shrub commonly found in Karachi, Sind, and Kutch in Pakistan. Its various parts are reputed for their medicinal properties in folk systems of medicine. The leaves are used in prurigo, eczema, impetigo, and acute gonorrhea, and the roots are used as a substitute for sarsaparilla, antiperiodic in fevers, tonic, alterative, and diuretic, and are given for chronic rheumatism and syphilitic cachexia (1-3). Previous investigations on various parts of the plant resulted in the isolation of trilobine (4,5), isotrilobine (5), coclaurine (4,5), magnoflorine (5), β-sitosterol, ginnol (6), and a monomethyl ether of inositol (6). As a result of our continuing investigations on C. hirsutus (7), we have isolated a new isoquinoline alkaloid, cohirsitinine, to which structure 1 has been assigned on the basis of extensive nmr studies (8-10). The ¹H-nmr assignments were made with the help of 2D COSY-45 and J-resolved and homonuclear decoupling experiments, and its relative stereochemistry has been determined by a series of nOe difference and NOESY experiments.