The Oyster Bay branch is the Long Island Rail Roads second least used branch (after the West Hempstead Branch) with 6,860 passengers per day east in 2017. Electrification on the branch has never been completed, making it the only diesel branch in Nassau County. Oyster Bay Branch base off peak service is provided by C3 trains to and from Jamaica normally every 2 hours on weekdays and weekends. During Peak hours service is more frequent (roughly every 30 minutes in the peak direction) with two trains extended to and from Hunterspoint Avenue (one continues in passenger service to Long Island City) and one dual-mode train round-trip per day to and from New York-Penn Station providing a single daily one seat ride from the heart of Manhattan to all stations on the Oyster Bay Branch.

The 14 mile long branch was double tracked between 1905 and 1911 from the branches start at Mineola to Locust Valley, where the remaining 3.9 miles are single-tracked (with the last single track intermediate station Mill Neck closing in 1998 due to low ridership warrenting a high-level platform being too costly) into Oyster Bay to this day. The line began becoming electrified in June 1934 between East Williston and Mineola but electrification was never extended farther north to Oyster Bay. East Williston received high-level platforms in the 1970s to allow M1 electric trains to operate into it (see below), but the rest of the branch didn’t receive high-level platforms until the late 1990s in preparation for the conversion of diesel service to the high-level platforms only BiLevel C3 trains.

Before 1970, when electrification was finally extended on the Main Line out to Huntington, East Williston had a few electric trains per day running to and from the station, by the October 30, 1972 timetable just one AM rush hour electric train remained on the Oyster Bay Branch. Train 1501 scheduled to depart East Williston at 7:30am. This electric train which ran pretty much on all timetables until timetables were reduced as of the March 29, 2021 due to the COVID-19 pandemic. Train 1501 originated in East Williston and made all local stops it could into Penn Station. These stops were Mineola, Merillon Avenue, New Hyde Park, Floral Park, the train then skipped Bellerose entirely because only Hempstead Branch trains can stop at Bellerose, before continuing with local service stop Queens Village, Hollis, Jamaica, Forest Hills, Kew Gardens, Woodside, and Penn Station.