ABSTRACTSome reports have demonstrated an inadequate response to hepatitis B vaccination in patients affected by celiac disease. The aim of our study was to evaluate hepatitis B vaccination response in relation to gluten exposure status in patients with celiac disease. To measure the gluten exposure status at the time of vaccination, we considered three groups: group A (exposed to gluten), including patients vaccinated as 12-year-old adolescents (the celiac disease diagnosis was established after vaccination); group B (not exposed to gluten), including patients vaccinated as 12-year-old adolescents on a gluten-free diet at the time of vaccination; and group C (infants), including patients vaccinated at birth. The response of celiac patients to hepatitis B vaccination was compared to that of healthy subjects, i.e., those in the control group (group D). This study included 163 celiac patients (group A, 57 patients; group B, 46 patients; and group C, 60 patients) and 48 controls (group D). An inadequate response to hepatitis B immunization was present in 43.9% of patients in group A, 34.8% of patients in group B, 58.3% of patients in group C, and 8.3% of patients in group D (group A versus group D,P< 0.001; group B versus group D,P= 0.002; group C versus group D,P= 0.001) (no significant difference for group A versus group B and group A versus group C was evident). Our data suggest that gluten exposure does not influence the response to hepatitis B immunization and that the human leukocyte antigen probably plays the main immunological role in poor responses to hepatitis B-vaccinated celiac patients.