Košariská (Hungarian: Kosaras) is a village and municipality in Myjava District in the Trenčín Region of north-western Slovakia.
In historical records the village was first mentioned in 1786.
The municipality lies at an altitude of 249 metres and covers an area of 11.531 km². It has a population of about 403 people.
The records for genealogical research are available at the state archive "Statny Archiv in Bratislava, Slovakia"
- Roman Catholic church records (births/marriages/deaths): 1788-1910 (parish B)
- Lutheran church records (births/marriages/deaths): 1720-1952 (parish A)