thumb|Location of Bouches-de-l'Yssel in France (1812)
Bouches-de-l'Yssel (; "Mouths of the IJssel"; ) was a department of the First French Empire in the present-day Netherlands. It was formed in 1810, when the Kingdom of Holland was annexed by France. Its territory corresponded with the present-day Dutch province of Overijssel. Its capital was Zwolle.
The department was subdivided into the following arrondissements and cantons (situation in 1812):
- Zwolle, cantons: Hasselt, Kampen, Steenwijk, Vollenhove and Zwolle.
- Almelo, cantons: Almelo, Delden, Enschede, Goor, Oldenzaal and Ootmarsum.
- Deventer, cantons: Deventer, Hardenberg, Ommen and Raalte.
Its population in 1812 was 145,000, and its area was 340,000 hectares.