This genus is thick-bodied and ratlike. It has large, broad ears and slender limbs, hands, and feet. The incisor teeth are ungrooved and pale yellow. The short, slightly curved, sharp-tipped claws are almost concealed by the long white hairs of the feet. Unlike some of its relatives, Mystromys does not have cheek pouches.
Females have two pairs of inguinal mammae.
The white-tailed rat inhabits grassy flats and dry sandy areas. It lives in holes in the ground. It has been observed using the burrows of the carnivore Suricata. It also shelters in cracks in the soil. It is nocturnal and is said to be especially active and bold during rainy weather.