The antibacterial activity of epigallocatechin gallate (EGCg), a main component of Japanese tea extract, was evaluated against 71 clinical isolates ofHelicobacter pylori recovered from patients with gastric ulcer disease at our hospital. The minimal inhibitory concentration (MIC) was distributed between 8 and 128 μg/mL, and the MIC90 was 64 μg/mL. The combination efficacy of EGCg with an anti-ulcer drug, plaunotol, was evaluated for antibacterial activity againstH. pylori. With addition of 6 μg/mL of plaunotol, the MIC for EGCg decreased significantly in all strains tested. tested. These results suggested that the combination of EGCg and plaunotol could be a useful regimen in the treatment of gastric ulcer.