The Pearl River is a river in the U.S. states of Mississippi and Louisiana. It forms in Neshoba County, Mississippi from the confluence of Nanih Waiya and Tallahaga creeks. and has a meander length of . The lower part of the river forms part of the boundary between Mississippi and Louisiana. The river contains large areas of bottomland hardwood swamp and cypress swamp, providing habitat for many species of wildlife including sturgeon and black bears. There was once hope that Ivory-billed woodpeckers might survive here, but this now seems unlikely. The mouth of the river provides important marsh habitat along salinity gradients; these marshes have been the subject of many scientific studies. It is considered to be one of the most critical areas of natural habitat remaining in Louisiana.