Long Island MacArthur Airport (IATA: ISP, ICAO: KISP, FAA LID: ISP), formerly known as Islip Airport, is a public airport in Ronkonkoma, in the Town of Islip, in Suffolk County, on Long Island, New York, United States. Covering 1,311 acres (531 ha), the airport was established in 1942, was activated in 1943, and began serving as a commercial airport in 1960. It has three runways and two helipads.

Owned and operated by the Town of Islip, MacArthur Airport serves Nassau and Suffolk counties as an alternative to John F. Kennedy and LaGuardia airports – both of which are located in the Borough of Queens in New York City. Shuttle buses connect the airport to the Long Island Rail Road's Ronkonkoma station.

The Federal Aviation Administration (FAA) designated LIMA an Official Metro Airport in early 2011, meaning it is now grouped with LaGuardia, Kennedy, and Newark in travel and informational searches for New York airports, thus providing better exposure. MacArthur Airport does not share the congested airspace of the city-centric airports, and it has an exceptional record of on-time performance. In 2009, 83.6% of flights arrived on time and 85.6% of flights departed on time.

In 2016, it had 124,154 aircraft operations, an average of 340 per day; 84% general aviation; 7% scheduled airline; 6% air taxi and 2% military. In 2017, the airport served more than 1.29 million airline passengers.