The present invention relates to a machine and a method for manufacturing composite filters. In the machine and the method for manufacturing composite filters (F1, F2) for cigarettes or the like, a feed conveyor (S) supplies filter groups (G1, G2) in pairs to two respective feed lines (L1, L2) of a station (16) for forming two continuous filter rods (B1, B2); the machine (100) comprises at least one transfer device (DT) by which the filter groups (G1, G2) are taken up from the feed conveyor (S) and directed along the feed lines (L1, L2), and at least one release device (R), operating along the two feed lines (L1, L2), by which the two filter groups (G1, G2) are taken up from the transfer device (DT) and released in phase one with another along the selfsame feed lines (L1, L2); the rate at which the filter groups (G1, G2) are released by the release device (R) is governed according to the phase value of at least one of the continuous filter rods (B1, B2) relative to the cyclic cutting operation whereby the two filter rods (B1, B2) are cut transversally to make the composite filters (F1, F2).