IOU
IOU or IOU is:
- an English expression for promissory note (phonetically IOU and I owe you are identical)
- an abbreviation for the Internationale Olympiajolle-Union , the class association of the Olympic boat class from 1936, see O-Jolle .
- an abbreviation for the input output unit, part of the computer, see input and output
- Name of a song from 1983 by the British band Freeez, see IOU (song)
- an abbreviation for the International Ornithologists' Union (formerly International Ornithological Committee)