Kalinowski's mouse opossum is a small marsupial known from a limited number of sites in northern South America. Few specimens are known, and the current name may include more than one species.
The back and sides are gray to cinnamon-brown, while the underside is cream to white. A large black mask crosses the face to the ears, and the tail is mostly naked and scaly.
It is described as arboreal and nocturnal, but behavioral records are very limited and its diet is unknown. Habits of related species should not be assumed for it.
An extinction-risk assessment has not been added yet.