长岛铁路（Long Island Railroad，LIRR）为美国纽约长岛居民提供铁路服务。长岛铁路是全美最忙碌的通勤铁路，每年载客量为8千1百万人次，是美国铁路系统中仍然使用原始名称的最老的系统。其以位于曼哈顿的宾夕法尼亚车站为主要端点总站向东延伸出总共八条支线，并以长达1,100公里（683.51英里）的铁轨连接共124个车站。纽约大都会运输署营运维护以及拥有长岛铁路。

The Long Island Rail Road (reporting markLI), legally known as the Long Island Rail Road Company and often abbreviated as the LIRR, is a commuter rail system in southeastern New York, stretching from Manhattan to the eastern tip of Suffolk County on Long Island. With an average weekday ridership of 337,800 passengers in 2014, it is the busiest commuter railroad in North America. It is also one of the few commuter systems in the world that runs 24 hours a day, 7 days a week, year-round. It is publicly owned by the Metropolitan Transportation Authority, as MTA Long Island Rail Road. The current LIRR logo combines the circular MTA logo with the text Long Island Rail Road, and appears on the sides of trains. The LIRR is one of two commuter rail systems owned by the MTA, the other being Metro-North Railroad. Established in 1834 and having operated continuously since then, it is the second oldest U.S. railroad still operating under its original name and charter.