This paper shows the analysis of a multihop Fast Frequency Hopping/Spread Spectrum Multiple Access (FFH/SSMA) System in a selective fading channel, in which we consider the frequency correlation characteristics between the signals on the adjacent hopping frequencies of the desired and intersymbol interference and we also take into account of the effects of interference having close hopping frequencies. A multihop-FFH scheme in which several hopping frequencies are used in order to transmit one data symbol, can be classified into a serialhop-FFH and a parallelhop-FFH scheme. More precise bit error probabilities of the multihop-FFH/SSMA systems are theoretically derived with reducing approximation than the bit error probability corresponding to a conventional analysis using the hit probability. As a result, it is classified that the parallelhop-FFH/SSMA system can achieve the better performance of bit error probability than the singlehop and the serialhop-FFH/SSMA systems in a selective fading channel, while the serialhop-FFH/SSMA system can considerably improve the bit error probability over the singlehop and the parallelhop-FFH/SSMA system in an AWGN channel. The performances depend on the number of simultaneously accessing users. Moreover, the computer simulations confirm the theoretical results.