The chemical composition and antimicrobial activity of the essential oil of the Balkan endemic species Seseli rigidum Waldst. & Kit. (Apiaceae) was investigated. The monoterpene alpha-pinene was predominant in the volatile oil from aerial parts (57.4%) and fruit (23.3%). In the essential oil of the aerial parts limonene (6.7%), camphene (5.8%) and sabinene (5.5%) were also present in high amounts, and in the fruit oil, beta-phellandrene (17.4%) and sabinene (12.9%). On the contrary, the root essential oil was composed almost entirely of the polyacetylene falcarinol (88.8%). The antimicrobial activity of the root essential oil was significant against Staphylococcus aureus, S. epidermidis, Micrococcus luteus and Enterococcus faecalis (MICs 6.25-25.00 microg/mL). Volatile constituents from the root strongly inhibited the growth of methicillin-resistant strains of S. aureus (MICs 6.25-50.00 microg/mL). Anti-staphylococcal activity can be attributed to the main volatile constituent ofS. rigidum root, falcarinol.