"What You Don't Know" is a song recorded by American Latin freestyle vocal group Exposé for their 1989 second studio album of the same name.

Written and produced by the group's founder Lewis A. Martineé, the lead vocals on "What You Don't Know" were performed by Gioia Bruno.

"What You Don't Know" was released as the lead single from the album on May 20, 1989, by Arista Records, and peaked at number eight on the US Billboard Hot 100 in July 1989, extending the group's streak of consecutive top-ten US pop hits to five.

[3] "What You Don't Know" features a prominent horn section accompanying the singers, and there is a guitar solo between the second and third verses.

Although the group continued to have success on the dance charts, this was one of the final Exposé pop hits featuring a beat, with which they had become associated from most of the singles off their previous album, Exposure (1987).