The Grorud Line is a 13.0-kilometer long (8.1 mi) line on the Oslo Metro between Tøyen and Vestli in Oslo, Norway. Built as a mix of underground, at ground level and as an elevated line, it runs through the northern part of Groruddalen, serving such neighborhoods as Grorud, Romsås and Stovner. Line 5 runs along the entire line four times per hour. Line 4 runs between Vestli and Økern before branching off on the Løren Line to get onto the Ring Line. With 40,000 daily riders, the Grorud Line is the busiest branch of the metro.

The Oslo Metro is the rapid transit system of Oslo, Norway, operated by Sporveien T-banen on contract from the transit authority Ruter. The network consists of five lines that all run through the city centre, with a total length of 85 kilometres (53 mi), serving 101 stations of which 17 are underground or indoors. In addition to serving 14 out of the 15 boroughs of Oslo, two lines run to Kolsås and Østerås, in the neighbouring municipality of Bærum. In 2016, the system had an annual ridership of 118 million.