The spirobenzylisoquinoline alkaloids (+)-sibiricine [1] and (±)-severzinine [3] have been isolated, for the first time, from the aerial parts of Corydalis flabellata. ¹H and ¹³C-nmr techniques, including ¹³C{¹H} nOe, have been employed to establish the relative stereochemistry of severzinine at C-8 and C-13 and to identify unambiguously chemical shift values for all H and C nuclei. As a consequence of this study, the resonance assignments reported previously for H-8 and H-13 of the closely related alkaloid 13-epi-yenhusomine [4] should be reversed, as should those for C-9 and C-10.