From the epigeal part of Thermopsis alterniflora, in addition to the alkaloids found previously, argentine, argentamine, and a new alkaloid, dimethamine, which is a representative of the bimolecular series, have been isolated. The structure of 3-(3′,4′-dihydro-N-methylcytisin-5′-yl)-N-methylcytisine has been proposed for dimethamine on the basis of IR, UV, mass, and NMR spectra and also from its conversion products. © 1974, Consultants Bureau. All rights reserved.