Megalobulimus K. Miller, 1878 is a genus of land snails that includes the largest living snails in the Neotropics. The main goal of this paper was to review all species of Megalobulimus that have a red lip, and which are distributed in Peru. We carried out a detailed description of their shells and soft parts, and conducted a multivariate analysis on their shells and geographic distribution. There are two species reported from Peru, Megalobulimus capillaceus (Pfeiffer, 1855) and Megalobulimus separabilis (Fulton, 1903). Megalobulimus capillaceus is known to occur in three regions - San Martín, Huánuco and Cusco - but the Cusco population is undoubtedly different from all remaining populations, and is recognized herein as a new species, Megalobulimus florezi sp. nov. This species has a more elongated shell, penis club-shaped, epiphallus longer, and free oviduct longer than M. capillaceus. By contrast, the male genitalia of M. separabilis is filiform and does not present an external diverticulum in the free oviduct.