Although the swimming behavior of Oryzomys palustris has been described, little is known about how long this species will remain in an area that is inundated by several centimeters of water. This study documents the response of an O. palustris population to habitat inundation in a coastal prairie locality of southeastern Texas. During a mark-recapture study conducted during 2002 and 2003, we live-trapped O. palustris on a grid in an area that experienced prolonged (≥5 mo) inundation during 2 of our 6 quarterly trapping periods. We describe a trapping technique, using foam rafts to support rodent live-traps, that is suitable for use in inundated areas. Despite long-term inundation, little available refuge, and an apparent complete turnover of the population, we estimated population densities of ca. 29 individuals per hectare during inundation, only a moderate decrease from the higher levels encountered before and after inundation.