A deterministic design approach for decentralized robust controls of a class of large-scale uncertain dynamical systems is proposed. The uncertainty under consideration can be fast time-varying; no aprioristatistical information is assumed or utilized. Only the possible bound of this uncertainty is known. Two important types of robust control algorithms are proposed. The local control utilizes the local state of each subsystem as the feedback information. The global control utilizes the local state as well as the states of the neighbouring subsystems as the feedback information. Both types of control algorithms are continuous functions of the state.