Mad River may refer to:

• Mad River (British Columbia), a river of British Columbia
• Mad River (Ontario), a river of Ontario

• Mad River (California)
• Mad River, California, a community in Trinity County, California
• Mad River (Connecticut), a river in New Haven County, Connecticut
• Mad River (Cold River), a tributary of the Cold River in Maine
• Mad River (Massachusetts), a river of Massachusetts
• Mad River (Cocheco River), a tributary of the Cocheco River in New Hampshire
• Mad River (Pemigewasset River), a tributary of the Pemigewasset River in New Hampshire
• Mad River (Ohio)
• Mad River Road, an overland route in Ohio
• Mad River (Vermont)
• Mad River Glen, a ski area in Vermont
• Mad River (Washington)

• Mad River (band), a rock band based in San Francisco, California during the 1960s
• Mad River (novel), a western novel by Donald Hamilton
• Mad River Brewing Company, a brewing company in California
• Mad River Local School District, in Riverside, Ohio, United States

• Erythropotamos, a river in Bulgaria and Greece known in Bulgarian as Luda reka ("Mad River")
• Mad River Township (disambiguation)
• All pages with titles beginning with Mad River