The species vary considerably in colour, being brown, reddish, dull orange, greyish, or blackish, but typically with lighter underparts.

The molar teeth have cylindrical crowns, with several islands and a single lateral fold of enamel.

Most species are brown on their backs and whitish or buff on their bellies; the fur may have a glossy appearance and then glimmers in an orange colour.

In Trinidad, they are renowned for being very fast runners, able to keep hunting dogs occupied with chasing them for hours.

Active and graceful in their movements, their pace is either a kind of trot or a series of springs following one another so rapidly as to look like a gallop.

They are regarded as one of the few species (along with macaws) that can open Brazil nuts without tools, mainly thanks to their strength and exceptionally sharp teeth.

Agoutis give birth to litters of two to four young (pups) after a gestation period of three months.

Fathers are barred from the nest while the young are very small, but the parents pair bond for the rest of their lives.