Amino acids are important to all animal life. Termites rely mainly on microorganisms to retrieve these nitrogen sources from their food. One naturally occurring amino acid, m-tyrosine, has been reported to be toxic to bacteria and weeds. Its direct effects on termite survival are unknown however. Both no-choice and choice bioassays using five different doses of m-tyrosine were conducted to determine the feeding response and survival of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), in the laboratory. In no-choice tests, although all doses of m-tyrosine tested reduced filter paper consumption, only the highest dose tested (0.05 M) had significantly lower consumption compared with the control. This dose also caused significantly high termite mortality. In a five-choice bioassay, all doses of m-tyrosine tested reduced filter paper consumption significantly compared with the control. No mortality was observed in the choice tests, and very little feeding of filter paper treated with m-tyrosine occurred. From these experiments, we conclude that m-tyrosine is toxic to Formosan subterranean termites and acts as a feeding deterrent, and therefore, may be a promising wood preservative.