Islip station was originally built as a South Side Railroad of Long Island depot in 1868.

[2] At the west end of the platforms is an at-grade pedestrian crossing with signals but no gates.

LIRR timetables from 1869 indicate it was at or near Brentwood Road,[3] 1.5 miles east of the Bay Shore station.

Warning lights and an audible signal alert passengers that a train is nearby, but no gates are present at the crossing area.

[citation needed] Ticket machines are located on the north side of the station building.