Marsh Creek is a tributary of the Portneuf River in Bannock County, Idaho, United States.
Beginning at an elevation of near Red Rock Pass, Marsh Creek flows generally north near the communities of Downey and Arimo. It parallels the Portneuf River starting near McCammon, reaching its mouth near Inkom, at an elevation of . It is roughly paralleled by Interstate 15/U.S. Route 91 in Idaho for most of its length.