C89

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