Linha do Vouga (the Vouga line) is the last surviving metre gauge railway line in Portugal still operated by Comboios de Portugal. The other remaining metre gauge lines (the Corgo, Tâmega and Tua lines) all closed in 2009. The line is, however, also under the threat of closure.
The Vouga line serves Aveiro, Agueda, Sernada do Vouga, Albergaria-a-Velha, Oliveira de Azeméis, São João da Madeira, Santa Maria da Feira, and Espinho.
Since 2002, services on the line have largely been operated by CP's Série 9630 diesel multiple units, which replaced the previous ex-Yugoslav Série 9700 diesel multiple units and the Dutch-built Série 9300 railcars.
The section between Sernada do Vouga and Viseu is closed.