The purpose of this thesis was to determine the antibacterial activity laurel (Laurus nobilis) essential oil and its hydrosol made against naturally occurring bacteria and Listeria innocua and antiadhesive activity against L. innocua on lettuce leaves. We assessed effect of essential oil and hydrosol on biofilm of naturally present bacteria. Essential oil (0.25 ?l/cm2 or 25 ?l/ml) and hydrosol (10 ?l/cm2, 20 ?l/cm2 30 ?l/cm2) showed antimicrobial effect on naturally present bacteria. Essential oil (0.25 ?l/cm2 or 25 ?l/ml) and hydrosol (20 ?l/cm2, 30 ?l/cm2) also showed antimicrobial activity against L. innocua inoculated on lettuce leaves. Antiadhesive effect was shown by essential oil (0.13 ?l/cm2 or 12.5 ?l/ml, 0.25 ?l/cm2 oz. 25 ?l/ml) and hydrosol (20 ?l/cm2, 30 ?l/cm2) on L. innocua inoculated on surface of lettuce. The results of this study indicated that essential oil and hydrosol of laurel do have some biological activities on salad leaves, as seen by their influence on naturally occurring bacteria and L. innocua. According to these results further work should focus on mechanisms involved in antiadhesion activity in foods.