Background. The proliferative lesions of the Brunner's glands (BGs) are hyperplasia and hamartomas, and they are usually asymptomatic and very rarely diagnosed. The aetiology of these lesions is not yet clear. The aim of this study is to evaluate the clinical presentations of patients with BG hyperplasia and hamartomas and to assess the pathological features of these lesions in association with Helicobacter pylori (H. pylori). Methods. Our retrospective study included patients who underwent upper gastrointestinal system endoscopy between 2010 and 2015. The hospital records of 18 patients diagnosed with hyperplasia or hamartoma of BG were reviewed for the clinical and pathological findings. Data from patients with BG lesion were compared with 37 patients who had nonspecific duodenitis as the control group. Results. Female/male ratio in our study sample was 1/1. The age range was between 16 and 85 years with a mean age of 48.61. BG hyperplasia and hamartomas were found in 72.22 and 27.78% of the patients, respectively. The rate of H. pylori in gastric mucosa was 43.2% in the control group and 66.7% in the BG lesion group. In the BG lesion group, the rate of H. pylori was higher. H. pylori was identified in 60% of BG hamartomas and in 69.2% of hyperplastic BGs. Conclusion. Our study demonstrated that H. pylori may play an important role in the development of BG hyperplasia and hamartomas in association with chronic gastritis and duodenitis. This is probably due to chronic irritation.