An efficient finite-element methodology, which uses the energy perturbation concept for evaluating the decoupled weight functions (hI(II)) of a mixed-mode crack in an orthotropic material, is presented. The methodology is achieved by applying a single colinear virtual crack extension technique to a symmetric mesh in the crack-tip neighborhood with the crack lying on one of the elastic symmetry planes. The use of symmetric mesh permits analytical separation of all field parameters of stresses, strains, displacements, tractions, and strain energy release rates into Mode I and Mode II components within the symmetric mesh zone. Once the decoupled explicit weight functions are predetermined explicitly for a given crack geometry, the decoupled stress-intensity factors, KI(II), under any loading conditions can be evaluated efficiently and accurately by a sum of worklike products between the applied tractions and the explicit weight functions at their application locations. Comparing the decoupled stress-intensity factors (KI(II)) obtained from the predetermined explicit weight functions for the orthotropic crack with those of well-established literature data shows good agreement with identical crack geometry, loading, and orthotropic properties but with different approaches.