One hundred forty-nine persons with culture-confirmed H. pylori infection were enrolled in the study. Of these, 125 who had documented health encounters for at least 8 years before enrollment (84%) were included for analysis. The median age of participants was 46.5 years (range, 22.2 to 88.7 years). Eighty-two (66%) were women, and all were Alaska Natives. Pharmacy records were available for a median of 8.6 years (range, 8.0 to 9.6 years). A median of 11 (range, 0 to 68) antimicrobial courses was prescribed during the 8 to 10 years before enrollment (mean, 1.52 courses per year). For β-lactam antimicrobial agents and macrolide antimicrobial agents, the median number of courses prescribed was 5 (range, 0 to 31) and 1 (range, 0 to 11), respectively. The median number of courses for all other classes of antimicrobial agents prescribed (including metronidazole) was 3 (range, 0 to 30). Thirteen patients (10%) had received previous treatment for H. pylori infection in the 10 years before enrollment. Clinical symptoms included heartburn (75%), nausea (72%), vomiting (40%), and hematemesis (11%). Endoscopic findings included hemorrhagic or superficial ulcerations of the gastric mucosa in 56 patients (45%), duodenal ulcers in 4 (3%), and gastric ulcers in 8 (6%).