Analytical solutions for calculating the adhesive fracture energy from wedge-peel tests, where significant energy is absorbed by deformation of the substrates, are outlined. These are based on the analysis by Williams [12]. A range of structural adhesives, with fracture energies between 600 and 5300 J/m(2), were used to bond aluminium-alloy substrates of thickness 1 or 2 mm, and tested using a range of pin diameters (i.e., wedge thicknesses). Three analysis methods were used, based on measuring either the radii of curvature of the substrates, the crack length or the force-per-unit-width during the test. All three methods gave good agreement with the independently measured values of the fracture energies (via linear elastic fracture mechanics). The methods were applied successfully to both cohesive and interfacial failure. The method using the force-per-unit-width was the easiest to apply, and gave the best agreement with the independently measured fracture energies.