A direct-sequence ultra-wideband impulse radio (DS-UWB-IR) system is developed for low-power wireless applications such as wireless sensor networks. This system adopts impulse radio characterized by a low duty cycle, and a direct-sequence 0.7-GHz bandwidth, which enables low-power operation and extremely precise positioning. Simulation results reveal that the system achieves a 250-kbps data rate for 30-m-distance wireless communications using realistic specifications. We also conduct an experiment that confirms the feasibility of our system.