At variance with current descriptions stressing the stellate geometry of cortical astrocytes in the brain of adult mammals, GFAP-immunoreactive astrocytes from prefrontal and rostral cingulate cortices in two adult New World monkey species, Cebus apella and Saimiri sciureus, were found to have long cellular processes traversing several cortical lamina. These unreported features of cortical astroglial cells in adult nonhuman primates pose new issues for the understanding of iso- and allocortical organization and processing in higher mammals.