We determined the in vitro susceptibility of clinical isolates of Helicobacter pylori to ZnCl, compared its sensitivity to bismuth subsalicylate (BSS) and clarithromycin (CLR) that are used for the treatment of H. pylori infection and its activity at different gastric pH. One hundred sixteen clinical isolates of H. pylori strains were chosen. Agar gel dilution method was used to determine the susceptibility of H. pylori isolates to ZnCl 40 μg/ml, BSS 20 μg/ml, and CLR 2 μg/ml. Suspension of 109 bacteria/μl was streaked on the blood agar plate. The control consisted of H. pylori incubated without ZnCl, BSS, and CLR. One hundred ten H. pylori strains (95%) were susceptible to ZnCl 40 μg/ml compared to 114 (98%) to BSS 20 μg/ml (p=0.002) and 92 (79%) to CLR 2 μg/ml (p=0.602). H. pylori isolates from patients with nonulcer dyspepsia and from peptic ulcer were equally susceptible to ZnCl 40 μg/ml (90/96 vs. 26/26, p=0.208). H. pylori associated with chronic gastritis and chronic active gastritis were equally susceptible to ZnCl. H. pylori demonstrated susceptibility to ZnCl in vitro. H. pylori susceptibility to ZnCl 40 μg/ml was greater than BSS and comparable to CLR. ZnCl may be used in the treatment of H. pylori infection.