The  A 4  is a Portuguese motorway which runs from Matosinhos to Amarante, with a length of 63 km, where it narrows to become signed as the IP road of which, by now, forms a part,  IP4 . The motorway leaves the metropolitan area of Porto, through the urban areas of Ermesinde, Valongo, Paredes, Penafiel, until arriving at the mountainous town of Amarante. It is also known as one of the most dangerous motorways in the country, particularly the descent from Campo to Valongo. Many improvements are being projected by the government in this respect. Currently is being extended into Bragan a and the border with Spain, to be opened in 2012, and will include the Portugal's longest road tunnel with 5,6 km, throughout Serra do Mar o, as well as a bridge which reaches an height from the ground of 230 m. It will be also the third longest motorway of Portugal with 223 km long.

de:Autoestrada A4 es:Auto-estrada A4 fr:Autoroute portugaise A4 pt:A4 (autoestrada) sk:Autoestrada A4 zh:A4 ( )