C89 may refer to:
Science and technology
- C89 (C version) or ANSI C, a C programming-language revision
- NGC 6087 (Caldwell catalogue: C89), an open cluster in the constellation Norma
Other uses
- Ruy Lopez (ECO code: C60–C99), a chess opening
- Night Work (Women) Convention (Revised), 1948, an ILO convention
- Sylvania Airport (FAA LID), Wisconsin, US
See also
- HMNZS Royalist (C89), a 1942 New Zealand Royal navy cruiser
- KNHC, a radio station in Seattle, Washington known as C89.5