The manatees are considered to be opportunist herbivors, consuming a great amount of alimentary items. The aim of the present study was to identify the alimentary components of the diet of Antillean manatees in free life in the northeastern region of Brazil. Samples of stomach contents from six Antillean manatee carcasses were col¬lected, in addition to fecal samples from 11 native manatees and five that had been released. The material was identified at the genus and/or species level, based on its morpho-anatomic aspects, and 21 species of seaweeds, phanerogams and cnidarians were presented. Through these analyses it was possible to observe that Antillean manatees fed on a great variety of aquatic plants, with the predominance of red seaweeds.