It is a silvery brown colour with pale streaks and russet underparts, and is very similar in appearance to the cotton-top tamarin, from which it is separated by the Atrato River.

Some authorities, such as Thorington (1976), posit that S. leucopus is very closely related to the cotton-top tamarin, Saguinus oedipus.

[4] Other analyses made by Hernandez-Camacho & Cooper (1976), and later Mittermeier and Coimbra-Filho in 1981,[4] and finally Grooves (2001)[5] This view is supported by Hanihara & Natoria's multivariate analysis of toothcomb dental morphology (1987) and by Skinner's work in 1991, which found high similarity between S. oedipus and S. leucopus in 16 out of 17 morphological traits considered.

[6] Philip Hershkovitz proposed that the divergence of the two species occurred in the Pleistocene at the height of the Atrato River, where it intersected the Cauca-Magdalena.

At this time, the area was covered by a sea, which created a geographic barrier which caused this ancestral species to diverge from S. oedipus through the process of allopatric speciation.

[8] Its diet consists of insects, soft fruits, and nectar,[8] plant exudates, prey animals, and flowers.

[2] The forests in which the white-footed tamarin lives are disappearing rapidly as the land is used for logging and mining, cleared for agriculture and for the construction of roads and dams.