Antitermitic activity of Taiwania (Taiwania cryptomerioides Hayata) against Coptotermes formosanus Shiraki was demonstrated in laboratory tests. Blocks of sapwood and heartwood from T. cryptomerioides exhibited antitermitic activity. Bioassays revealed that heartwood essential oil exhibited the highest antitermitic activity, followed by sapwood essential oil and then the n-C6H14 soluble fraction when tested at 10 mg/g. The order of termite mortality of three compounds purified from n-C6H14 soluble extracts of heartwood was cedrol > alpha-cadinol > ferruginol. The termite resistance of T. cryptomerioides wood can be attributed to the termiticidal activity of cedrol and alpha-cadinol.