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. © 1992, American Chemical Society. All rights reserved.