Two new species of Eugenia (Myrtaceae) are described from the Masoala Peninsula in Madagascar: Eugenia williamsiana and Eugenia ambanizanensis. Each has relatively large leaves among Malagasy taxa of the genus. Both species are presently known from only two collections, but since they occur in a well-protected area they are considered Least Concern under IUCN guidelines. Features of the inflorescence and floral morphology of E. ambanizanensis are atypical for Eugenia and are discussed in light of the putatively related genera Stereocaryum, Monimiastrum, and Plinia. A tentative key is provided for species of Eugenia from Madagascar in which some or all of the mature leaves are in excess of 15 cm in length. Based on published and unpublished DNA sequencing data, five species of Monimiastrum are transferred into Eugenia.