Tehuantepec (Spanish pronunciation: [tewanteˈpek], in full, Santo Domingo Tehuantepec) is a city and municipality in the southeast of the Mexican state of Oaxaca. It is part of the Tehuantepec District in the west of the Istmo Region. The area was important in pre Hispanic period as part of a trade route that connected Central America with what is now the center of Mexico. Later it became a secondary capital of the Zapotec dominion, before it was conquered by the Spanish in the early 16th century.

The city is still the center of Zapotec culture in the Isthmus of Tehuantepec and is the second largest in the region. The city is known for its women and their traditional dress, which was adopted by Frida Kahlo. Tehuantepec has a reputation for being a matriarchal society. Women dominate the local markets and are known to taunt men. However, political power is still the domain of men.

The city experienced a short economic boom in the early 20th century related to a rail line that was built linking the two oceans, but it was soon eclipsed by the Panama Canal. There have been plans to resurrect the line linking the Gulf of Mexico and Pacific Ocean but financing has been a problem.