If multipath delay difference is greater than the duration of a cyclic prefix, the performance of the orthogonal frequency division multiplexing (OFDM) system suffers severe degradation. The insufficient cyclic prefix phenomenon incurs 2 adverse interferences, intersymbol interference (ISI) from the adjacent symbols and intercarrier interference (ICI) from other subcarriers in the same OFDM symbol interval. In this paper, we propose the novel decision feedback equalizer (DFE) receiver to improve the performance of OFDM system with insufficient cyclic prefix. The proposed receiver does not require the knowledge of channel impulse response. Simulation results confirm the advantages of our proposed receiver over the TEQ technique.