Piauí (Portuguese pronunciation: [piawˈwi]) is one of the states of Brazil, located in the country's Northeast Region.

Piauí has the shortest coastline of any of the non-landlocked Brazilian states at 66 km (41 mi), and the capital, Teresina, is the only state capital in the northeast to be located inland. The reason for this is, unlike the rest of the area, Piauí was first colonised inland and slowly expanded towards the ocean, rather than the other way around. In the southeast of the state, the National Park of Serra da Capivara is a UNESCO World Heritage Site. The park has more than 400 archaeological sites and the largest concentration of rock paintings in the world, in a landscape dominated by canyons and caatinga.