Spin-spin splittings are analyzed for two nonequivalent electron spins. The resulting equations are applied to the simulation of the EPR spectra of spin-labeled copper complexes exhibiting electron-electron coupling. The electron-electron coupling and z components of the electron-nuclear couplings are treated exactly. The off-diagonal (x, y) components due to electron-copper nuclear coupling are treated as a perturbation, to second order for the transition energies and first order for the transition probabilities. The field dependence of the energy separation, (g1 - g2)βH, for the two electron spins is included. Calculated and observed spectra for a spin-labeled derivative of copper(II) bis(acetylacetonato)ethylenediamine are in good agreement.