Berberine, obtained from phellodendron amurense, was used in traditional Japanese dyeing to give a yellow colour. Experiments suggest that the relation between the amount of berberine adsorbed on the silk and the concentration of berberine in the dye bath fit the freundlich equation. Dyed silk cloths were exposed to direct sunlight for from 0.5 to 64 hours. Colour differences, diffuse reflectance spectra and fluorescence spectra were measured before and after exposure. The intensity of fluorescence decreased with increasing exposure time, and it is suggested that when fluorescence is present it could be useful for controlling the extent of fading. In addition, extracts from the most faded sample were examined, using thin-layer and liquid chromatography and ir analysis, for light-induced degradation of berberine. Some decomposition products were detected and characterised. References.