Three new species of Magnolia from lowland tropical rain forests of south-eastern Mexico are described and illustrated: Magnolia chimalapana, M. heribertoi and M. uxpanapana. We contrast these with morphologically similar species. The three new species are endemic to the Chimalapas region and are evaluated as critically endangered (CR). A map of published Magnolia species from the Chimalapas-Uxpanapa region and key for the Mexican species of M. section Talauma are also provided.