Infection by Helicobacter pylori is prevalent in approximately half the world´s population.However, the susceptibility of H. pylori to antimicrobial agents must be evaluated by in vitro methods in order to determine the susceptibility levels and to guide treatment regimes.The prevalence of infection and antibiotic susceptibility was evaluated in gastric biopsies containing H. pylori.The prevalence of infection and antibiotic susceptibility was investigated in 203 patients with chronic gastritis from Tumaco, Colombia. Diagnosis was confirmed by histopathological evidence (Dixon scale) and microbiological (culture on blood agar supplemented with antibiotics).The antibiotic resistance of H. pylori was measured by its response toantimicrobial amoxicillin and clarithromycin using the agar dilution method.The prevalence of infection for H. pylori with histopathological and microbiological tests was88.7% and 84.7% respectively. The prevalence of resistance of H. pylori to antimicrobial amoxicillin was 20.5%, to clarithromycin 19.8%, and to both antibiotics concurrently, 10.9%.A high incidence of clarithromycin-resistant and amoxicillin-resistant H. pylori was discovered in patients from Tumaco with chronic gastritis. Dual drug-resistant strains of H. pylori to clarithromycin and amoxicillin were also present.