The roots of T. alpinum L. yielded twelve tertiary alkaloids of which two are new natural products, thalpindione (1), the second reported dioxobisbenzyltetrahydroisoquinoline alkaloid, and N-desmethylthalrugosidine (5); the others were thalidasine (3), thalrugosidine (4), thalicarpine (9), thalrugosaminine (10), neothalibrine (11), O-methylisoboldine (12), isoboldine (13), N-methyl-6,7-dimethoxyisoquinolone (14), oxyberberine (15), and noroxyhydrastinine (16). Thalpindione was O-methylated to thalrugosinone (2), a recently reported new alkaloid, and N-desmethylthalrugosidine (5) was N-methylated to thalrugosidine (4). Location of the unmethylated nitrogen in 5 was established by Na/NH3 cleavage of the O-ethyl derivative 6 to fragments 7 and 8. From the quaternary alkaloid fraction six alkaloids were obtained, palmatine (17), berberine (18), columbamine (19), jatrorrhizine (20), thalifendine (21), and magnoflorine.