Three alkaloids, northalicarpine (1), thalflavidine (4) and N-methyl-laurotetanine (5) were isolated from the roots of Thalictrum revolutum. Northalicarpine (1), a new natural product, was characterized from spectral data, confirmed by methylation to thalicarpine (2) and by sodium/ammonia cleavage to 2'-hydroxy-4',5',6,7-tetramethoxybenzyltetrahydroisoquinoline (3), and is the first discovered N-desmethyl aporphine-benzylisoquinoline alkaloid. Thalflavidine (4), a phenanthrene alkaloid previously reported from T. pacum L., was identified by spectral characteristics comparison, with T. revolutum being the second reported source. N-methyl-laurotetanine (5), already reported from the tops of T. revolutum, was identified by direct comparison of physical data with those from a known sample.