This article presents a study based on the Tsai-Wu failure criterion as well as Hankinson's formula that evaluates the off-axis strength of wood. For materials such as wood, the strengths are a function of the grain orientation and also are different in compression and tension for the same direction. By considering this anisotropic behaviour, the failure criterion of the Tsai-Wu was adopted in this work. To establish this criterion, the strengths were determined from compressive and tensile tests as well as shear and biaxial compressive tests. In addition, off-axis uniaxial tests were performed, and the experimental results were compared with those obtained by the discussed criteria. In these tests, specimens of Goupia glabra-Brazilian wood species were used. This study's most important conclusion was: the predictive ability of the Tsai-Wu criterion was close to that of Hankinson's formula and fits the experimental results of the compressive and tensile tests well. © 2012 Copyright Taylor and Francis Group, LLC.714958Ashkenazi, E.K., Problems of anisotropy of strength (1965) Polymer Mechanics, 2 (1), pp. 60-70(1997) NBR 7190: Design of wood structures (Rio de Janeiro: ABNT/Brazil), , Associação Brasileira de Normas Técnicas, Rio de Janeiro, Brazil. in PortugueseBodig, J., Jayne, B.A., (1982) Mechanics of Wood and Wood Composites, , Malabar: Krieger Publishing CompanyClouston, P., Lam, F., Barret, J.D., Interaction term of Tsai-Wu theory for laminated veneer (1998) Journal of Materials for Civil Engineering, 10 (2), pp. 112-116Clouston, P., Lam, F., Barret, J.D., Incorporating size effects in the Tsai-Wu strength theory for Douglas-fir laminated veneer (1998) Wood Science and Technology, 32, pp. 215-226Cowin, S.C., On the strength anisotropic of bone and wood (1979) Journal of Applied Mechanics, 46, pp. 832-838Cramer, S.M., Hearmonson, J.C., Mcmurthy, M., (1996) Characterizing large strain crush response of redwood, , Sandia report. SAND96- 2966.UC-820, Sandia National Laboratories.[check]Eberhardsteiner, J., (2002) Mechanisches Verhalten von Fichtenholz- Experimentelle Bestimmung der biaxialen Festigkeitseigenschaften, , (Vienna: Springer) (In German)(2004) Design of Timber Structures-Part 1-1: General Rules and Rules for Buildings, , European Committee for Standardization (EUROCODE 5). (Brussels, Belgium: CEN, European Committee for Standardization)Galicki, J., Czech, M., Tensile strength of softwood in LR orthotropy plane (2005) Mechanics of Materials, 37, pp. 677-686Hasebe, K., Usuki, S., Application of orthotropic failure criterion to wood (1989) Journal of Engineering Mechanics, 4 (115), pp. 867-872Hoffman, O., The brittle strength of ortotropic materials (1967) Journal of Composite Materials, 2, pp. 1200-1206Liu, J.Y., Evaluation of the tensor polynomial strength theory for wood (1984) Journal of Composite Material, 18, pp. 216-226Mascia, N.T., Nicolas, E.A., Todeschini, R., Evaluation of off-axis wood compression strength (2007) International Conference on Experimental Mechanics, 1, pp. 1-8. , Greece European Association for Experimental Mechanics (EURASEM), AlexandroupolisMurray, Y.D., (2007) Manual for ls-dyna Wood Material Model 143, , McLean, VA: US Department of Transportation, FHWA-HRT-04-097. Office of Safety Research and Development -Federal Highway AdministrationNicolas, E.A., Study of anisotropic failure criteria applied to wood (2006), Campinas: PhD. thesis, State University of Campinas (in Portuguese)Norris, C.B., The elastic theory of wood failure (1939) Transactions of ASME, New York, 3 (61), pp. 259-261Suhling, J.C., (1985) Constitutive relations and failure predictions for nonlinear orthotropic media, , PhD. thesis, University of WisconsinTsai, S.W., Wu, E.M., A general theory of strength for anisotropic materials (1971) Journal of Composite Materials, 1, pp. 558-580Woodward, C., Minor, J., Failure theories for Douglas-fir in tension (1988) Journal of Structural Engineering, 12 (114), pp. 2808-2813