Marshfield is a city in Wisconsin. It is the largest city in Wood County, but it straddles the border between Wood County and Marathon County, Wisconsin. The population was 18,800 at the 2000 census.

Marshfield is home to the Marshfield Clinic and the Central Wisconsin State Fair, as well as the World's Largest Round Barn. Marshfield is located at the intersection of U.S. Highway 10 and Wisconsin State Highways 13 and 97.

Together with surrounding communities, the Marshfield micropolitan area was, according to the 2000 census, home to 27,408 people. The city forms one of the core areas (the other is at Wisconsin Rapids) of the United States Census Bureau's Marshfield-Wisconsin Rapids Micropolitan Statistical Area, which includes all of Wood County (2000 population: 75,555). Although some of the communities included in the Marshfield micropolitan area (as distinct from the Marshfield-Wisconsin Rapids mSA) are in neighboring Marathon County, these are included in the Wausau, Wisconsin MSA, which includes all of that county, rather than in the Marshfield-Wisconsin Rapids mSA, which exclusively includes Wood County.