A new alkaloid, delphisine, has been isolated from the seeds of Delphinium staphisagria by a combination of pH extractions and chromatographic techniques. Chemical and spectral studies have suggested that it is a member of the aconitine-type alkaloids. An x-ray crystal structure determination of its hydrochloride confirmed it to be an aconitine-type alkaloid, with 1α-hydroxyl, 6α-methoxyl, 8β-acetate, 14α-acetate, 16β-methoxyl, 18-methoxyl, and N-ethyl substituents. The space group is P212121, a = 13.866 (1), b = 22.27 (1), c = 9.098 (1) Å. The final agreement residuals are R = 0.0351 and Rw = 0.0400, based on 2875 observed reflections. The absolute configuration of delphisine is shown to be 1S, 4S, 5R, 6R, 7R, 8R, 9R, 10R, 11S, 13R, 14S, 16S, 17R. Ring A was found to exist in the boat conformation, stabilized by intramolecular hydrogen bonding. Spectral studies showed that this conformation exists in solution as well, and suggested that the previously published structure of neoline is in error. Neoline was prepared from delphisine by several routes. Comparison of both neoline and delphisine with their 1-epimers showed that neoline must have a 1α-hydroxyl group. On the basis of other well-established chemical correlations, the structures of chasmanine and homochasmanine must also be revised to show a 1α substituent. © 1976, American Chemical Society. All rights reserved.