Phase noise destroys the orthogonality between sub-carriers in orthogonal frequency division multiplexing (OFDM) systems and creates intercarrier interference (ICI), which results in performance degradation. In this paper, partial response signaling (PRS) is used to reduce the effect of ICI caused by phase noise. The expression of ICI power with PRS is derived and the optimum PRS coefficients that minimize the ICI power are obtained. The simulation results show that the optimum PRS for OFDM systems obviously reduce the ICI power without decreasing the bandwidth efficiency.