Periodic controllers designed based on the so-called lifting technique are usually represented by transfer matrices. realtime operations require that the controllers be implemented as periodic systems. We study the problem of realizing an Nni x Nni proper rational transfer matrix as an ni-input no-output N-periodic discrete-time system. We propose an algorithm to obtain periodic realizations which have a minimal number of states. The result can also be used to remove any redundant states that exist in a periodic system.