Pinosylvin (3,5-dihydroxy-stilbene) and Pinosylvin monomethyl ether (3-hydroxy-5-methoxy-stilbene) were formed by cells in callus tissue cultures of Pinus resinosa Ait., when these cells were subjected to desiccation leading to death over a period of time at 25 °C. Pinosylvin and Pinosylvin monomethyl ether were absent in check cultures growing under normal conditions at the same temperature.The significance of the above findings is discussed in relation to the theory of "protection wood formation" in trees as well as for biochemical studies on the biosynthesis of heartwood phenols in trees.