AbstractFailure criteria from six theories were applied to estimate the shear strength of the adhesive line in terms of grain slope when under loaded tension stress. The shear stresses of the adhesive line as a function of the angle of the wood grain were determined by experimental tests. Specimens were obtained from 12 Eucalyptus saligna wood beams. They were prepared with varying angles of the grain (0°, 15°, 30°, 45°, 60°, 75°, and 90°) in relation to load application, following the requirements of the Brazilian standard. From the results of the six failure criteria and experimental results, robust statistical analysis was carried out; it was thus possible to adapt the models to determine the shear strength of the adhesive line as a function of the angle of the wood grain. The six mathematical models evaluated do not show statistical significance (p < 0.05) in their original format. With modifications, the models showed statistical significance only with the formulations of DIN 1052 and Karlsen.