Abstract The chemical composition of the essential oil of the seeds of Oenanthe crocata, an endemic plant of Sardinia and Corsica, has been studied by analytical and spectroscopic methods. Some terpenes, 1,8-cineole, camphor, 1-octyn-3-ol-3-methyl, 8,10-heptadecadiene-4,6-diyne-1,12-diol have been isolated. The cytotoxic, antiviral and antimicrobic activities of the oil have also been evaluated. The oil did not show a significant antiviral activity, but showed a moderate antibacterial activity against Streptococcus faecalis and Bacillus lentus.