Cassistrellus yokdonensis was described from Yok Don National Park in Vietnam. Two specimens were captured in lowland, dry, open dipterocarp forest.
Its dorsal fur is short, sparse, and clove-brown; the underside is beige, the throat cream-colored, and the wing tips narrow and pointed.
Two bats were caught at night in large canopy nets in lowland, dry, open dipterocarp forest.
An extinction-risk assessment has not been added yet.