BACKGROUND To study basal gastrin levels in duodenal ulcer patients and in those with normal endoscopy, according to Helicobacter pylori infection. METHODS Eighty-four duodenal ulcer patients and 164 with normal endoscopy were studied. Biopsy specimens were taken from gastric antrum and body, and investigated for microbiology (Gram stain and culture) and histology (hematoxilin-eosin stain). Basal gastrin levels were measured (RIA). RESULTS In duodenal ulcer patients the percentage of chronic gastritis was higher (p < 0.001) than in patients with normal endoscopy without H. pylori infection, and similar to patients infected by H. pylori. In patients with normal endoscopy (n = 164), those infected with H. pylori (n = 115) had higher (p = 0.02) gastrin levels (mean +/- SD) than non-infected (64 +/- 34 vs 51 +/- 14 pg/ml) and similar to duodenal ulcer patients (62 +/- 20 pg/ml). In the multiple regression model analysis H. pylori infection was the only variable which correlated with gastrin levels (regression coefficient 9.48 [SE = 4.59]; multiple correlation coefficient 0.22 [p = 0.008]). Additional variables (age, sex, duodenal ulcer) were not correlated with gastrin levels. Patients with chronic gastritis had higher gastrin levels (p < 0.01) than those with normal histologic mucosa. CONCLUSIONS In patients with normal endoscopy, those infected with H. pylori had significantly higher basal gastrin levels than non-infected individuals, and similar to duodenal ulcer patients. Therefore, hypergastrinaemia seems to be associated with H. pylori infection, and is not a distinctive feature of duodenal ulcer disease.