The East Rail line is one of the ten lines that form MTR, the mass transit system in Hong Kong. The railway line starts at Lo Wu or Lok Ma Chau, both of which are boundary crossing points into Shenzhen and joins in the north at Sheung Shui and ends at Admiralty station on Hong Kong Island. At approximately 46 km (29 mi), the line is the second longest line within the network, behind the Tuen Ma line. The line's colour is light blue, formerly navy blue before the KCR/MTR merger.

The Mass Transit Railway (MTR) is a major public transport network serving Hong Kong. Operated by the MTR Corporation (MTRCL), it consists of heavy rail, light rail, and feeder bus services, centred around a 10-line rapid transit network, serving the urbanised areas of Hong Kong Island, Kowloon, and the New Territories. The system encompasses 245.3 km (152.4 mi) of railways, as of December 2022, with 179 stations—including 99 heavy rail stations, 68 light rail stops and 1 high-speed rail terminus.