This study investigates the antiulcerogenic and antibacterial activities of Apium graveolens extracts. The antiulcerogenic activity was evaluated in rats by the HCl/EtOH method. Inhibition of gastric lesions by A. graveolens extracts was dose-dependent for both aerial part (53-76%) and seeds (51-95%). The methanolic extract as well as the aqueous extracts used at 300 mg kg(-1) dose exhibited a highly significant inhibition of gastric lesions (91% and 95%, respectively) which was similar to that induced by omeprazole (94%). Essential oil and aqueous extract prepared from the aerial parts of A. graveolens were tested to determine their antibacterial activity using the paper disc-diffusion method, the minimal inhibitory concentration and the minimal bactericidal concentration. Essential oil of A. graveolens was strongly inhibitory against Escherichia coli and moderately inhibitory against Pseudomonas aeruginosa and Staphylococcus aureus. The chemical composition of the volatile oil was investigated by gas chromatography analysis. The major components identified were β-pinene, camphene, cumene, limonene, α-thuyene, α-pinene, β-phellendrene, p-cymene, γ-terpinene, sabinene and terpinolene.