In this study we have investigated the role of Epr, a minor extracellular serine protease, in the swarming motility of Bacillus subtilis 168. We identified that the protease activity of Epr was dispensable for swarming. Since the protease activity of Epr was confined to its N-terminal domain, we hypothesized instead that its C-terminal domain (CTD) could be critical for swarming. Our study showed that not only the expression of Epr-CTD was necessary, but also its secretion was crucial for the swarming motility of B. subtilis 168.