The Brazilian arboreal mouse (Rhagomys rufescens) is a South American rodent species of the family Cricetidae.

The hallux (big toe) bears a nail rather than a claw, a unique characteristic of this genus.

[4] R. rufescens was first described in 1886 from Rio de Janeiro State in Brazil but it has not been found in that locality for over one hundred years and was believed to be extinct.

Several specimens were caught in pitfall traps sunk in the ground, but it is thought that it is an arboreal rodent, or one that scrambles among the undergrowth, because of the morphology of its feet.

Examination of the stomach contents of one individual that was caught showed that it had eaten several species of ant.