The Sumatran mountain rat is known from high mountains on Sumatra. Current specimen records are limited to two mountains, including a record from montane or moss forest.
Like the other related highland Rattus on Sumatra, it has long dark fur with a dense, woolly underfur.
Both known specimens were collected above 2,000 m; the second came from montane or moss forest. No other museum specimens were known to the authors, so details of its life remain sparse.
An extinction-risk assessment has not been added yet.