The Vendsyssel Line or the Vendsyssel Railway (Danish: Vendsysselbanen) is a 80.7 km (50.1 mi) long standard gauge single track railway line in Denmark which runs through the historical region of Vendsyssel between Aalborg and Frederikshavn. It constitutes the northernmost part of Den Østjyske Længdebane, the through route through the Jutland Peninsula from Padborg to Frederikshavn.
The section from Nørresundby to Frederikshavn opened in 1871. In 1879 the route was continued from Aalborg to Nørresundby over the Limfjord as the Limfjordsbroen railway bridge was inaugurated.
The Vendsyssel line runs north from Ålborg to Hjørring and turns east from there to Frederikshavn, making the rail distance about 80 km, where the road distance is about 60 km. The line is owned and maintained by Rail Net Denmark and served with passenger trains by the Danish State Railways (DSB) and local and freight trains by Nordjyske Jernbaner. The southernmost section from Aalborg to Lindholm is also served by the Aalborg Commuter Rail.
Vendsyssel is the northernmost traditional district of Denmark and of Jutland. Being divided from mainland Jutland by the Limfjord, it is technically a part of the North Jutlandic Island. Vendsyssel is part of the North Denmark Region.
Vendsyssel neighbours Hanherred to the southwest and Himmerland to the south, across the Limfjord. Whether the island Læsø is also a part of Vendsyssel, is a matter of definition. The major towns of Vendsyssel are Hjørring, Frederikshavn, Brønderslev, Sæby, Hirtshals, Løkken, Nørresundby and, on its northern tip, Skagen. The dominating city is, however, Aalborg which is mainly situated outside Vendsyssel on the southern shore of the Limfjord with Nørresundby as a secondary, northern centre.
Adam of Bremen (ca. 1075) calls Vendsyssel Wendila, Ælnoth (ca. 1100) calls it Wendel, the Icelandic literature Vendill. Derived from this is the ethnic name wændlar, Danish vendelboer, which is part of the name of the syssel. In the Danish Census Book (Kong Valdemars Jordebog, ca. 1231) Wændlesysæl, Wendelsysel, Wændil. Presumably originally the name of the Limfjord, then name of the region north of it. According to historians and linguists, the name Vendsyssel may be derived from the Germanic tribe of the Vandals. Syssel is an ancient form of administrative region. Vendel (Old Danish Wændil) was also the ancient name of the Limfjord itself.