Junceine, a new alkaloid isolated from the seed of Crotalaria júncea is hydrogenated in the presence of a catalyst to tetrahydrojunceine. This product is a salt of retronecanol and a monobasic acid, junceic acid. The infrared absorption spectra of junceine, tetrahydrojunceine and junceic acid resemble closely those of trichodesmine, tetrahydrotrichodesmine and trichodesmic acid, respectively. By alkaline degradation junceine, like trichodesmine, gives methyl isobutyl ketone Junceine absorbs two mole-equivalents of periodic acid in contrast to trichodesmine which absorbs only one. In this oxidation of junceine, formaldehyde is formed thus indicating the presence of a CH2OH group. The chemical and physical properties of junceine and its degradation products lead to the conclusion that junceine is an hydroxyl derivative of trichodesmine. © 1956, American Chemical Society. All rights reserved.