By-elections for Prague 4 and Znojmo District Senate seats were held in the Czech Republic in October 2004.

Elections were held after incumbent senators became members of European parliament.

[1] Election in Prague 4 was won by František Příhoda who defeated Erazim Kohák by landslide.

[2] Znojmo election was unexpectedly won by Milan Špaček.

He faced Jaroslav Pařík who was considered front-runner due to his results in the first round.