Like the common and widely introduced european house mouse, it is a member of the enormous superfamily Muroidea, which includes over 1000 different species.

[1] Grey to brick-red overall, it is pale on the underside and has small but prominent triangular ears.

Its method of sex determination has also been found to differ from most mammals[2] in that rearrangements of the X chromosome have led to many XY individuals actually being female.

They live in colonies or in pairs in grass close to water and are excellent climbers.

Pygmy mice are often kept as pets, but require social interaction, so should always be kept as pairs or small colonies.