Aims: Duodenal nodularity is an uncommon endoscopic appearance of numerous visible mucosal nodules in the proximal duodenum. In this retrospective study we aimed to determine the clinical significance and histopathologic features of duodenal nodularity in children. Materials and Methods: The medical records of the patients who were defined to have duodenal nodularity by endoscopy were reviewed. Statistical Analysis Used: The data were expressed as mean SD and percentages (%). Results: Seventeen patients with endoscopically defined duodenal nodularity were chosen. The mean age at diagnosis was 12.1 years (range: 6-17 years), 9 males. Abdominal pain (47%) was the most common clinical symptom and antral nodularity (41%) was the most common endoscopic finding in children with duodenal nodularity. Histopathologic evaluation of duodenal nodules revealed chronic inflammation in all patients, increased intercryptal and intraepithelial numbers of eosinophils in 70.5%, and villous atrophy in 47% of patients. Giardia infestation was demonstrated in 6 patients by histologic examination and/or Giardia lamblia-specific antigen positivity in stools. The clinical diagnoses of the patients have shown variations, such as celiac disease, giardiasis, secretory IgA deficiency, and Helicobacter pylori gastritis, and some of them were associated with the others. Conclusions: Although the endoscopic appearance is similar, clinical spectrum and pathologic features are not so similar and there are no specific histomorphologic findings for nodularity. The most demonstrative findings we observed in children were increased lymphocyte and/or eosinophil infiltration in the duodenal mucosa. We suggested that care should be taken in the evaluation of microbiological and immunologic etiologies causing this prominent inflammatory reaction.