GOALS: We retrospectively studied all seropositive Marsh 1 patients seen at 2 tertiary care hospitals in the last 15 years to determine their clinical, serological, and histologic outcomes. BACKGROUND: Patients with positive celiac serologies and Marsh 1 histology represent an understudied subgroup of patients, and it is unclear whether they should be advised to adopt a gluten-free diet (GFD). STUDY: Subjects were identified based on positive celiac serologies and Marsh 1 histology while on a full-gluten diet. Clinical presentation and baseline laboratory data were noted. Clinical course, repeat serologies, and histology were determined. RESULTS: Of 620 patients with positive celiac serologies and abnormal duodenal histology, we identified 36 (5.8%) with positive tissue transglutaminase and/or antiendomysial antibodies and Marsh 1 lesions who had adequate follow-up. Abdominal pain was the commonest (47.2%) presenting symptom. Twenty-eight patients were advised to adopt GFD, whereas 8 were not. Among patients treated with GFD, 88.9% improved symptomatically and 95% normalized serology. In contrast, among patients who continued to consume gluten, 85.7% remained symptomatic and 80% had persistently positive serologies. Among the 8 patients on normal diet, 5 underwent repeat biopsy, and 4 of them had the same or worse histology, with 3 patients progressing to Marsh 3c. Among the 28 patients on GFD, 5 underwent repeat biopsy and all improved to normal histology. CONCLUSIONS: Most patients with positive celiac serology and Marsh 1 lesions benefit from GFD and, if not treated, a majority will continue to be symptomatic and remain at risk of progressing to villous atrophy.