Essential oils from species of the genus Hyptis are well-known for their significant biological properties, including antimicrobial and acaricidal activities. The essential oil from the aerial parts of H. crenata was obtained by hydrodistillation; bomeol (17.8%), 1,8-cineol (15.6%) and p-cimene (7.9%) were characterized by GC-MS as its major constituents. The essential oil was evaluated in vitro for its antimicrobial activities against six fungal and five bacterial strains, by measuring the respective MICs, MFCs and MBCs, using broth microdilution methods. The strongest bactericidal activities were shown against Staphylococcus aureus and Enterococcus faecalis, while the strongest fungicidal activities were against Cryptococcus neoformans, Candida glabrata and Candida tropicalis. The oil was also assessed for its anti-tick properties and, at a concentration of 2.5%, it significantly inhibited in vivo oviposition of engorged females of the cattle tick Rhipicephalus (Boophilus) microplus, using the adult immersion test., with an effectiveness of 94.4%.