There are described and illustrated four species of Myrtaceae from Amazonian Brazil: Eugenia altoalegre, from the state of Roraima, and Eugenia fortuita, Myrcia amanana and Plinia tapuruquarana, these three from the state of Amazonas. Eugenia altoalegre is related to E. tachirensis, being distinguished by its larger, acuminate blades and inflorescences with two or more flowers; Eugenia fortuita is related to E. spruceana, but has larger inflorescences and densely pilose flowers; Myrcia amanana is related to M. splendens, but has a greyish floccose indumentum, and Plinia tapuruquarana is related to P. pinnata, but has wider blades, thicker petioles and larger flowers. Additionally, conservation issues are discussed for each species.