The Trans-Sahelian Highway or TAH 5 is a transnational highway project to pave, improve and ease border formalities on a highway route through the southern fringes of the Sahel region in West Africa between Dakar, Senegal in the west and Ndjamena, Chad, in the east.

It is one of two east–west transnational links in West Africa and runs inland from and, for most of its length, roughly parallel to the Trans–West African Coastal Highway with a separation of about 900 km (559 mi).

The Trans-Sahelian Highway has a length of about 4,500 km (2,800 mi) running through Senegal, Mali, Burkina Faso, Niger, Nigeria, and the far northern tip of Cameroon, ending at N'Djamena just inside the western border of Chad.

All but about 775 km (482 mi), mostly in western Mali, has been paved, but extensive sections elsewhere require rehabilitation or are currently under reconstruction.

Paved roads connect the Trans-Sahelian and West African Coastal Highways through