Summary: We propose an arbitrary-length linear-phase cosine-modulated filter bank (CMFB). It can be considered as an extension of the existing linear-phase CMFBs to arbitrary length. It is shown that the 2M-channel arbitrary-length linear-phase CMFB needs to satisfy the same conditions as the conventional M-channel arbitrary-length CMFB does for perfect reconstruction. By using the linear-phase property of a prototype filter, we obtain an efficient implementation structure in which \(2\times 2\) lossless lattices are used instead of \(2\times 1\) ones in the traditional implementation of the existing linear-phase CMFBs. The total number of the lattices is reduced by a half.