Essential oils and their components are becoming increasingly popular as naturally occurring antimicrobial agents. In this work the chemical composition and the antibacterial properties of Nigella sativa essential oils (EO) and of their main components were determined. The essential oil components were identified by GC-MS analysis. The antibacterial activity of the essential oil was determined against a panel of strains bacteria, using a broth microdilution method. The GC-MS analysis showed that the major constituents of the oil were monoterpene hydrocarbons and phenolic monoterpenes, and results of antibacterial activity confirmed the possibility of using Nigella sativa essential oils or some of their components in biology and pharmaceutic preparations.