Bouches-de-l'Yssel (Dutch: Monden van de IJssel) is the name of a département of the First French Empire in the present Netherlands. It is named after the mouth of the river IJssel. It was formed in 1810, when the Kingdom of Holland was annexed by France. Its territory corresponds with the present Dutch province Overijssel. Its capital was Zwolle. The département 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.