In this letter, we propose a multi-user detection scheme based on a hidden training sequence for DS-UWB systems. The hidden training sequence, which uses a fraction of the informative sequence's transmitting power as training information, is utilized for the receiver filter adaptation and channel estimation. By using this, the proposed scheme offers increased bandwidth efficiency (no period dedicated for training) and also shows reasonably good performance and near-far resistance in single and multiple-access UWB indoor multipath channel environment.