The goal of this paper is to rehabilitate the genus Monvillea, based on Cereus cavendishii as the type species, which identity has been attributed to another genus. The name Cereus cavendishii Monville corresponds to a species of northern Argentina, Paraguay, eastern Bolivia and southern Brazil, as had been considered traditionally in the literature, and that species was typified accordingly by Heath in 1992. As a consequence, Monvillea keeps its nomenclatural validity. Additionally, an epitype is here designated. The inclusion or not of all or some of the species in Monvillea under Cereus is a taxonomic matter, and hence a matter of opinion, but the pertinence of Cereus cavendishii to Monvillea sensu Britton and Rose cannot reasonably be disputed.