Six alkaloids have been isolated from the Lythraceae plant Lagerstroemia indica L. and structures have been assigned to all of them on the basis of spectroscopic and degradative studies. Three of the alkaloids-deca-mine, decinine, and decodine-were isolated previously from Decodon. Dihydroverticillatine had not been isolated previously; it had been prepared by the catalytic hydrogenation of verticillatine. Lagerstroemine (I, R = H) is a new methoxylation pattern in the verticillatine series of alkaloids. Lagerine (V, R = H) has a biphenyl ether quinohzidine skeleton which differs from that of any known Lythraceae alkaloid; however, this structure is consistent with current biogenetic theory. © 1971, American Chemical Society. All rights reserved.