The effect of magnetic islands on the propagation of lower hybrid waves is investigated analytically for a model slab equilibrium with a single helical perturbation corresponding to anm=1 orm=2 island. From the variation ofk∥inside the island, the parallel current is estimated with the same pitch as the original perturbation. The effect of such a current on the nonlinear evolution of anm=2 island corresponds to a destabilization of the mode if the rf driven current is in the same direction as the global parallel current. A comparison with numerical solutions of the problem using a toroidal ray trajectory code is also presented.