The Slavonic Dances was an Earth musical composition by composer Anton Dvorak. Data was engaged in an analysis of Dvorak's collected works in 2369 and The Slavonic Dances was one of his areas of focus.
When Data's positronic subprocessor experienced a power surge during an interface with the USS Enterprise-D's main computer, it caused many of his personal files to replace library files on the computer. One result was that Captain Picard's own composition, the Picard Mozart trio, Program 1, was partially overwritten with The Slavonic Dance No. 8, Opus 46. A progressive memory purge eventually restored the files to their original condition. (TNG: "A Fistful of Datas")