During the investigation of ethanolic and chloroform extracts from Cadia purpurea [1, 2] by TLC on silicagel and detection by jodoplatinate, an alkaloid was noticed, differing from the others by its greenish-blue color. Although the concentration seemed to be very small, it still appeared possible to isolate this alkaloid by means of column-chromatography (on alumina, Woelm neutr.; elution with ether : chloroform 95 :5) and to purify it by preparative TLC on silicagel (Merck Fertigplatten; cyclohexane : diethylamin 7 : 3). The thus obtained alkaloid was identified as 13-ethoxylupanin by TLC and MS in comparison with a synthetic sample, made by condensing 13-hydroxylupanin with ethanol, via the tosyl-derivative. Rl values: 0.58 on Merck silicagelsheets; cyclohexane : diethylamin 7 : 3. 0.68 id; Benzene : ethylacetate : diethylamin 5 : 4 : 1 0.56 id.; Toluene : acetone : ethanol : ammonia 40 : 40 : 8 : 3. MS - data: M' 292.2147 (de 291, 263, 247, 211, 180, 156, and further conform hydroxylupanin). The synthetic made 13-ethoxylupanin probably possesses the e-position, in contrary with the authentic sample. The reversed intensity of the masspeaks 263 and 247 in the masspectra of both alkaloids, may be due to this a- or e-position. Difference in Rf - values has not been observed. For the time being there is no sufficient material collected to determine other physical data. To the best of my knowledge the isolation of 13-ethoxylupanin from a natural source seems not to have been reported earlier.