Collagenous gastritis is a rare disorder, with only 8 cases reported in the literature, 2 in children and 6 in adults. We report an additional case of collagenous gastritis in a 42-year-old man with celiac disease. A thickened (>10 μm) subepithelial collagen band with entrapped capillaries, fibroblasts, and inflammatory cells was seen in the stomach, associated with lymphocytic gastritis. The duodenal mucosa showed severe villous atrophy but no subepithelial collagen deposition. No evidence of lymphocytic or collagenous colitis was found in the colon. The patient became symptom-free on a gluten exclusion diet and showed partial improvement of histopathologic findings after 3 months. Collagenous gastritis is a rare disease, but a wider recognition of its histopathologic features and clinical associations may bring more cases to light and provide additional clues in determining its etiology and pathogenesis.