The aim of the present study is to assess the chemical composition, as well as the antioxidant, antimicrobial and cytotoxic activity of essential oils extracted from four Myrtaceae species grown in Brazil. Chemical composition assessment has evidenced the prevalence of terpenic compounds, such as α and β-pinene, d-limonene, O-cymene, β and γ-elemene, β-caryophyllene and curzerene, in the investigated species. The best antioxidant potential was observed for Eugenia uniflora L. essential oil based on the DPPH, ABTS and FRAP tests; this species was followed by Myrciaria tenella (DC.) O. Berg, Myrcianthes gigantea (D. Legrand) D. Legrand and Myrcia oblongata DC. The best antimicrobial activity levels were recorded for M. tenella, M. gigantea and E. uniflora, respectively, which presented broad spectrum of inhibitory, bactericidal and fungicidal activity. The cytotoxicity test has evidenced the cytotoxic effect of essential oils on human cancer cells (H295R lineage); the lowest inhibitory concentrations were observed for M. gigantea and E. uniflora. Remarkable chemical diversity of terpenic compounds was found in essential oils extracted from Myrtaceae species, which showed antioxidant, antimicrobial and cytotoxic activity.