A new tetrahydroprotoberberine alkaloid, 2,10-dihydroxi-3,10-dimethoxy-8 beta-methyldibzo[a,g]quinolizidine (hemiargyrine), was isolated from Croton hemiargyreus. Other bases present were glaucine, oxoglaucine, salutaridine and norsalutaridine. Their structures were elucidated using spectroscopic techniques. (C) 1998 Elsevier Science Ltd. All rights reserved.