Erythramine and two new alkaloids, named erythraline and erythratine, have been isolated from the seeds of Erythrina glauca Willd. Erythraline was also isolated from the seeds of Erythrina fusca Lour., Erythrina Folkersii Kruk. and Mold., Erythrina variegata L. var. orientalis (L.) Merr., Erythrina velutina Willd., and Erythrina macrophylla DC. Hypaphorine was isolated from all of the above mentioned species and all for the first time, with the exception of Erythrina variegata var. orientalis from which it had been previously isolated by others. Erythraline and hypaphorine undoubtedly exist also in Erythrina velutina forma aurantiaca (Ridl.) Kruk. and Erythrina Grisebachii Urb. The crystalline erythraline and erythratine bases, their hydrobromides and hydriodides, have been described. Many microanalyses on several samples and from different species have shown that erythraline has the empirical composition C18H19NO3, and erythratine has the empirical composition C18H21NO4. Erythraline and erythramine were of comparable activity (7-8 mg./kg.) in causing a curare-like paralysis in frogs, whereas, erythratine had one-tenth of this activity. © 1940, American Chemical Society. All rights reserved.