Crack extension in elastic-plastic material involves energy dissipation through the creation of new crack surfaces and additional yielding around the crack front. An analytical procedure, using a two-dimensional elastic-plastic finite element method, was developed to calculate the energy dissipation components during a quasi-static crack extension. The fracture of an isotropic compact specimen was numerically simulated using the critical crack-tipopening-displacement (CTOD) growth criterion. Two specimen sizes were analyzed for three values of critical CTOD. Results from the analysis showed that the total energy dissipation rate consisted of three components: (I) the crack separation energy rate G,, (2) the plastic energy dissipation rate Gr, and (3) the residual strain energy rate G,,. All three energy dissipation components and the total energy dissipation rate initially increased with crack extension and finally reached constant values. For ductile materials (larger CTOD), Gr, becomes dominant (more than 70"/0 of the total), whereas G,, remained constant (ahout 6%). Furthermore, Gr, appeared to vary linearly with the plastic zone height. G, is linearly proportional to the critical CTOD.