Ammodaucus belongs to the family Apiaceae (Umbelliferae), subfamily Apioideae, trib Caucalideae, and comprises one species in Algeria (Quezel and Santa, 1962).The biological importance of members of this genus promoted us to reinvestigate the volatile constituents of the fruits of Ammodaucus leucotricus Coss. et Dur., and to carry out a biological study as far as the antibacterial activity is concerned. The present work deals with the chemical composition and antibacterial activities of the hydrodistilled oils. After extraction, the oil was analyzed by gas chromatography–mass spectrometry to afford 14 components. The major components were found to be, 1-cyclohexene-1-carboxaldehyde (56.40%), D-limonene (28.82%), and 2-pentanone-4-hydroxy-4-methyl (5.73%). Moreover, the antimicrobial activities of the volatile oils were evaluated by disk diffusion method against Gram-positive and Gram-negative bacteria. The results showed a strong antibacterial activity against Staphylococcus aureus, Escherichia coli and Klebsiella pneumonia.