On the basis of a general sampling formula it is shown that, for a system ofnband-limited signals, FDM and band-limited TDM are equivalent in the sense that one can be derived from the other by a simple linear transformation. The transformation matrix is the same as for expanding an arbitrary polyphase system withnphases into its symmetric components. It is further shown that this equivalence also holds for nonideal sampling waveforms as they appear in certain multiplexing and demultiplexing systems used in practice.