The effects of a black wood stain, caused by one or more fungi, on the natural resistance of Alaskan yellow cedar (AYC), Chamacyparis nootkatensis (D. Don) Spach, to the Formosan subterranean termite, Coptotermes formosanus Shiraki, were studied. Feeding and survival of groups of 300 C. formosanus feeding on unstained Alaskan yellow cedar heartwood and sapwood and fully and partially black-stained heartwood were compared with a control group feeding on loblolly pine, Pinus taeda L., wood. All termite groups feeding on unstained AYC died by the end of 14 wk. At the end of 32 wk, mortality of termite groups feeding on fully and partially black-stained AYC was significantly higher than that of groups feeding on pine. Termite mortality was significantly higher when feeding on partially than on fully black-stained AYC at the end of 32 wk. Wood consumption was significantly different among all treatment groups, with means of 4.07, 8.76, 19.81, and 29.77 mg/d in the unstained, partially, and fully black-stained AYC, and loblolly pine, respectively. This suggests that toxic and feeding deterrence properties of AYC heartwood were significantly reduced by black-staining fungus infection but were not totally lost. Chemical analysis of unstained and black-stained AYC wood showed approximately a 50% reduction in concentration of secondary chemicals in the black-stained wood. Carvacrol was totally absent in the black-stained wood. Concentrations of nootkatone in the black-stained wood were one-fourth of those observed in unstained AYC wood. Ecological implications are discussed.