The coat is soft, dense, and quite long. The upper parts are olive-brown, cinnamon brown, or mixed cream color and black, with the sides of the head and neck sometimes tinged with rufous. An indistinct, blackish dorsal stripe may be present. The underparts are reddish, buffy gray, or cream-colored over a blackish base. The tail is thinly covered with minute hairs.
Females have eight mammae.
Like Hylomys, this genus resembles certain microtine rodents in general appearance. From Hylomys, Neotetracus is distinguished by its longer tail, shorter snout, and fewer teeth. Neotetracus inhabits cool, damp forests from about 1,000 to 2,800 meters in elevation. It is apparently strictly terrestrial and nocturnal. It is common in parts of its range and is found in runways and burrows with moss and fern cover and under logs and rocks.