In this paper the wave method is used for designing high-order square-root domain filters, which emulate the topology of the corresponding LC ladder prototypes. This is achieved by transposing the signal flow graph that corresponds to the wave equivalent of the elementary two-port subnetwork in the linear domain to the corresponding one in the square-root domain, by employing an appropriate set of complementary operators. As the equivalents of the other reactive elements are derived from the wave equivalent of the elementary subnetwork, by interchanging the terminals of the appropriate wave signals and/or using inverters, an advantage offered by the proposed technique is the modularity of the derived filter configurations. As an example, a fifth-order lowpass square-root domain wave filter was designed and its behaviour was studied through simulation results in order to demonstrate the validity of the proposed design technique. (C) 2006 John Wiley & Sons, Ltd.