Oslo Commuter Rail (Norwegian: Lokaltog Østlandet) is a commuter rail centered in Oslo, Norway, connecting the capital to six counties in Eastern Norway. The system is operated by Vy (formerly NSB) and its subsidiary Vy Gjøvikbanen, using Class 69 and Class 72 electric multiple units (EMU). The network spans eight routes and 128 stations, with Oslo Central Station (Oslo S) as the central hub. The trains run on 553 kilometers (344 mi) of electrified mainline railway owned by the Bane NOR. Deficits are financed by the Norwegian Ministry of Transport, although the network also has a ticketing cooperation with Ruter, the public transport authority in Oslo and Akershus. The network is the longest commuter rail network in the Nordic countries, and among top ten in Europe.

The commuter rail operates mainly within Greater Oslo and two of the lines only provide services within the urban area. Six of the lines span beyond the urban area, reaching the counties of Østfold, Hedmark, Oppland and Buskerud. The system is also an airport rail link to Oslo Airport, Gardermoen. West of Oslo, the system uses the Drammen, Asker, Spikkestad and Sørland lines, north of Oslo it uses the Gjøvik Line, east of Oslo it uses the Trunk, Gardermoen and Kongsvinger lines and south of Oslo it follows the Østfold and Eastern Østfold lines.

The system's predecessors date back to the opening of the Trunk Line in 1854. By 1902, all the routes used by the present commuter rail had been taken into service. Electrification started in 1922, and Class 62 EMUs were introduced in 1931, followed by Class 65 units in 1936 and Class 67 in 1953. Electrification was completed in 1963. In 1980, the Drammen Line was connected to the rest of the system and all trains started operating to the new Oslo S. The high-speed Gardermoen Line opened in 1998. In 2013, new Stadler FLIRT units were taken into traffic, and the Asker Line was completed just before. In 2022, the Follo Line was opened.

Traditionally, Oslo Commuter Rail were defined as train lines called "Lokaltog" (local trains) in Norwegian. However, in 2022, a different definition was implemented. Only the two lines L1 and L2 are now defined as Lokaltog, and these go once per 15 minutes in each direction. All other lines in the network are now called "Regionaltog" (regional trains) and they have 30 or 60 minutes between departures and often take an hour from Oslo to the end station.

The Oslo Commuter Rail runs entirely on mainline railways owned and maintained by the Norwegian National Rail Administration. The commuter rail uses ten lines, utilizing a line length of 553 kilometers (344 mi). The lines are all electrified at 15 kV  16.7 Hz AC and consists of 128 stations. The Asker, Drammen, Gardermoen and Østfold lines, and part of the Trunk Line, have double track, accounting for 204 kilometers (127 mi), while the rest of the network has single track.

Oslo S is the central hub of the commuter rail. Located in the central business district of Oslo, all lines either terminate at, or run through the station. From Oslo S, there are four main corridors. All trains running through the West Corridor continue along either the North, South or East Corridor. Because there are more services in the latter three, some of these terminate at Oslo S. The line numbers for the commuter and the regional lines are such that those going along the Eastern and Western corridor (beyond Stabekk) have 1 and 10–14, those going along the Southern corridor have 2 and 20–22, and for the Northern corridor 3 and 30.

Along the West Corridor, the Drammen Line runs straight into the Oslo Tunnel, which starts directly beneath Oslo S. Trains run through Nationaltheatret, Norway's second-largest station, while in the tunnel. Just after surfacing, trains halt at Skøyen. One of the routes see their trains terminate at Skøyen, while the remaining nine continue onwards to Lysaker. After Lysaker, Line L1 continues stopping at all nine stations serving suburbs in Bærum and Asker, before reaching Asker Station, which serves as the terminus for most Line L1 services. For Line L1, Asker is 35 minutes and 24 kilometers (15 mi) from Oslo S.

Lines R12, R13 and R14 only call at Sandvika before Asker, and use the Asker Line between the two stations. Line R14 terminates at Asker. After Asker Station, Line L1 branches off along the Spikkestad Line and calls at six stations in Asker and Røyken before terminating at Spikkestad Station. Spikkestad is 44 minutes and 37 kilometers (23 mi) from Oslo S. Lines R12 and R13 continue through the Lieråsen Tunnel and make two more stops (R13) before reaching Drammen. Line R13 terminates at Drammen. Drammen is 39 minutes and 42 kilometers (26 mi) from Oslo S. Lines R12 continue, along the Sørland- and the Vestfold Lines, calling at seven stops in Eiker and Kongsberg before terminating at Kongsberg Station (R12).