Douro is a Portuguese wine region centered on the Douro River in the Trás-os-Montes e Alto Douro region. It is sometimes referred to as the Alto Douro (upper Douro), as it is located some distance upstream from Porto, sheltered by mountain ranges from coastal influence. The region has Portugal's highest wine classification as a Denominação de Origem Controlada (DOC) and is registered as a Protected Designation of Origin under EU and UK law, and as a Geographical Indication in several other countries through bilateral agreements. While the region is best known for Port wine production, the Douro produces just as much table wine (non-fortified wines) as it does fortified wine. The non-fortified wines are typically referred to as "Douro wines".

Alto Douro was one of the 13 regions of continental Portugal identified by geographer Amorim Girão, in a study published between 1927 and 1930. Together with Trás-os-Montes it became Trás-os-Montes e Alto Douro Province.

The style of wines produced in the Douro range from light, Bordeaux-style claret to rich Burgundian-style wines aged in new oak.