This study was carried out to determine the prevalence of antibodies to Helicobacter pylori in northern Nigeria, a region with a low incidence of peptic ulceration. In a random, serological survey of 268 subjects, 228 (85%) of the population studied had IgG antibodies to H. pylori. Fifty-eight of these subjects had experienced dyspepsia in the preceding 6 months. The majority of the population (82%) is infected between the ages of 5 and 10. Despite the high prevalence of antibodies to H. pylori, peptic ulcer is uncommon, suggesting that H. pylori is not important in the etiology of peptic ulcer in this population. Indeed, most patients infected by H. pylori are asymptomatic. The possible reasons for this are discussed.