IL-18, IL 18 or IL18 may refer to:
Interleukin 18, a protein encoded in humans by the IL18 gene Ilyushin Il-18 (1957), a Cold War–era Soviet turboprop airliner and military transport Ilyushin Il-18 (1946), a prototype Soviet radial-engined airliner Illinois's 18th congressional district, a defunct U.S. House district Illinois Route 18, a rural east–west state road in central Illinois, U.S.
See also