The volatile constituents of the aerial parts of Carum montanum (Coss. et Dur.) Benth. et Hook. were analysed by GC-FID and GC-MS, and the main component was isolated and identified as nothoapiole. The antibacterial and antifungal activities of this compound and of the total oil were investigated against Gram-negative (P. aeruginosa, E. coli), Gram-positive (E. faecalis, S. aureus, S. epidermitis, S. saprophyticus, S. simulans, S. lugdunensis) bacteria and on one strain of fungus (C. tropicalis).