Fast frequency hopping (FFH) is a very effective way to combat jamming. In this paper, low density parity check (LDPC) code is combined with diversity-combining techniques to enhance the performance of FFH systems under band multitone jamming (BMTJ). The optimum maximum-likelihood (ML) combining which needs perfect side information (SI), and various suboptimum combinings which need partial or no SI, are considered here. Simulation results show that the proposed LDPC coded frequency hopping system provides excellent performance against band multitone jamming.