In this work, we investigate the linear and the nonlinear Goursat problems. The solution of the Goursat problem is presented by means of the homotopy perturbation method (HPM). The application of HPM to this problem shows the rapid convergence of the sequence constructed by this method to the exact solution. The linear and the nonlinear structures are handled in a similar manner without any need to restrictive assumptions. The accuracy level of the obtained results reveals the power of this method over existing numerical methods. Copyright (C) 2009 John Wiley & Sons, Ltd.