One hundred and seventy-seven patients with insulin dependent diabetes mellitus (IDDM) diagnosed at the pediatric age were investigated for the presence of gastric parietal cell autoantibodies (PCA). The objective was to evaluate the prevalence of PCA seropositivity and to know whether Helicobacter pylori could be a reason for a higher presence of PCA in IDDM children and adolescents. Twelve of 177 patients (6.77%; confidence interval: 3.1-10.3) had detectable PCA. Gastric pathology was studied in eight of these patients and in seven patients without PCA. Diagnosis of H. pylori infection was made on antral biopsies. None of the patients had an atrophic gastritis. Six of the eight patients with PCA had gastric mucosa colonization by H. pylori and/or chronic gastritis. According to these results, we suggest that H. pylori can be the cause of the presence of PCA positive results in diabetic children and adolescents, and diabetic patients with detectable PCA should be screened for H. pylori