Southern Illinois Airport (IATA: MDH, ICAO: KMDH, FAA LID: MDH) is a public airport in Jackson County, Illinois, United States. It is located three nautical miles (6 km) northwest of the central business district of Carbondale and east of Murphysboro. This airport is included in the FAA's National Plan of Integrated Airport Systems for 2021–2025, which categorized it as a general aviation facility.

The airport opened in 1950 and was originally known as Murdale Airport.

The airport is owned and operated by Southern Illinois Airport Authority, a local governmental entity created under state law. A five-member board sets policy for the airport authority, and daily administration of the airport is carried out by an airport manager and staff. The board members are appointed by the mayors of Carbondale and Murphysboro and the Chairman of the Jackson County Board and serve for five years on a staggered basis.