Two new N-methyltetrahydroprotoberberines, (−)-N-O-dimethylthaicanine [1] and (−)-N-methylthaicanine [2] were isolated from Anisocycla cymosa leaves together with four other known alkaloids: (−)-N-methyltetrahydropalmatine [3], anisocycline [4], palmatine [5], and stephenanthrine [6]. Their structures and stereochemistry were determined by chemical and spectrometric methods, including 2D nmr experiments (13C-1H COSY and 1H-1H COSY). © 1992, American Chemical Society. All rights reserved.