ABSTRACT The Atlantic Forest is made up of different vegetation types over extensive latitude. Most of its remnants are in mountain ranges, which are responsible for the maintenance of most endemic and threatened species in this domain. Here we present the floristic composition of the Área de Proteção Ambiental Mestre Álvaro (APAMA), a coastal massif at Espírito Santo State with expressive altitudinal amplitude (100-800 a.s.l.) containing remnants never floristically studied. Knowing the composition of this protected area is important because it includes an altitudinal range not yet evaluated in floristic comparisons involving highland and lowland forests between the latitudes 18-21° S. We found 493 species (in 292 genera and 91 families): ten are regional endemic species, nine are new records of occurrence for the state, and 52 are under some degree of threat of extinction. Our results indicate the presence of flora elements' typical of both highland and lowland forests, which makes the APAMA essential in a scenario extremely fragmented. Finally, our data provide an unprecedented floristic list for regional forest restoration projects, as well as an invaluable source of data for biogeographic studies that seek to understand the effect caused by neighboring vegetation types on the composition of lowland forests.