São Luís Island, located in the north of the State of Maranhão is itself a transitional region between the Amazonian and the northeastern floras. With such phytogeographi-cal background, the aim of this paper was to realize a floristic survey on the sandy beaches of the São Luís Island and to compare this 'survey with other areas sampled along the Brazilian coast. A total of 260 species was found, distributed in 76 families, and among these the Fabaceae presenting the highest number of species (24). The floristic comparison showed that the State of Bahia has the highest number of species in common with São Luis (63), followed by the State of Pará (59). Among the species found in São Luís, 125 were exclusive of this area.
floristics; beach; diversity