Objective: Cymbocarpum erythraeum (Apiaceae) is an endemic species in Iran. Up to now, there have been no phytochemical and biological investigations on this species. Therefore, isolation of the main secondary metabolites of the plant along with its anti-H. pylori activity have been considered in this paper. Materials and Methods: The dried parts of the plant were extracted with different solvents using solvent percolation and the antibacterial activity of the extracts evaluated by the disk diffusion method. Four compounds were isolated using different column chromatography methods. Results: The compounds were identified by proton nuclear magnetic resonance and carbon-13 nuclear magnetic resonance as isoquercetin (1), rutin (2), β-sitosterol (3) and 2-decenol (4). Conclusion: Anti-H. pylori evaluation of the extracts and isolated compounds against three clinical isolates of H. pylori revealed that hexane extract of the plant inhibited all H. pylori strains.