The following five alkaloids have been isolated from Senecio jacobaea L. (ragwort) : seneciphylline, C18H23O5N ; jacobine, C18H25O6N ; jacozine, C18H23O6N ; jaconine, C20H32O7NCl; and jacoline, C18H27O7N. Jacodine which has been identified as seneciphylline, jacobine and jaconine have been isolated from this species by earlier workers, but jacozine and jacoline are new alkaloids.