During the course of studies on the alkaloidal constituents of orchidaceous plant, Dendrobium nobile LINDL.,1) it has been found that these consist of dendrobine2)(Ia), nobilonine3) (II), dendroxineo4)(IIIa), 6-hydroxy-dendrobine5)(dendramine6); Ib), and 6-hydroxy-dendroxine5) (IIIb). The structure of these alkaloids has been thoroughly investigated2-9) by chemical and spectroscopic means, and especially dendrobine (Ia) and nobilonine (II), two main alkaloids of this plant, have been correlated by a mutual interconversion.3)Gas chromatographic (GC) analysis of the crude basic principles of this plant revealed the presence of ten of substances, five of which have already been fully characterized (see Fig. 1). This report concerns the structure elucidation of the two minor components, i.e., 4-hydroxy-dendroxine (IIIc) and nobilomethylene (V), which remained unclarified.