稻大鼠（学名：Oryzomys palustris）是北美洲一种半水生的啮齿类。牠们主要分布在美国东部及南部，由新泽西州及肯萨斯州南部至科罗拉多州及墨西哥塔毛利帕斯州最东北端。；其分布地以往扩展至更西及更北的地方，与当地的玉米种植片利共生。牠们一般出没于潮湿的环境，如沼泽及盐沼。牠们重40-80克，属于中等身型，外观像黑鼠及褐鼠。牠们的上身一般呈灰褐色，但科罗拉多州群落的上身是赤色的。牠们的后脚拥有适合水中生活的特征。头颅骨很大及扁平，前部很短。

约翰·巴克曼（John Bachman）牧师于1816年发现稻大鼠，于1937年才有正式的描述。稻大鼠有几个亚种，主要都是来自科罗拉多州，但其有效性受到质疑。在佛罗里达礁岛群的群落有时会被看为另一物种：银色稻鼠（Oryzomys argentatus）。另外，库氏稻鼠与稻大鼠一同在塔毛利帕斯州及德克萨斯州南部出现。

The marsh rice rat (Oryzomys palustris) is a semiaquatic North American rodent in the family Cricetidae. It usually occurs in wetland habitats, such as swamps and salt marshes. It is found mostly in the eastern and southern United States, from New Jersey and Kansas south to Florida and northeasternmost Tamaulipas, Mexico; its range previously extended further west and north, where it may have been a commensal in corn-cultivating communities. Weighing about 40 to 80 g (1.4 to 2.8 oz), the marsh rice rat is a medium-sized rodent that resembles the common black and brown rat. The upperparts are generally gray-brown, but are reddish in many Florida populations. The feet show several specializations for life in the water. The skull is large and flattened, and is short at the front.