— The design of ultra-wideband (UWB) impulse radio receivers has to cope with complex signal propagation environments with dense multipath fading, which complicate channel estimation and multipath energy capture. As the date transmission rate increases, additional interference between adjacent symbols arises which may further degrade the detector performance. To address these problems, this paper presents a multi-symbols differential detector that is capable of mitigating inter-symbol interference (ISI) without requiring training or costly channel estimation. A reduced-complexity implementation based on the Viterbi algorithm is proposed, which offers adjustable parameters to balance between performance and complexity. Simulations under typical indoor operating environments demonstrate that the proposed UWB detection scheme is remarkably robust against the effects of both channel noise and ISI.