Southern yellow pine (<i>Pinus echinata</i>?) was found to yellow when exposed to wavelengths shorter than 350 nm and lignin underwent preferential decomposition by ultraviolet light. The extent of degradation was proportional to the light energy irradiated and increased as a function of irradiation time. No chemical changes, apart from photo-bleaching, were observed in wood exposed only to wavelengths longer than 400 nm. -- AATA