Refractory celiac disease (RCD) is subdivided into two subtypes (RCDI and II), based on a normal or abnormal phenotype of intraepithelial lymphocytes, respectively. RCDII is the most severe form and seems to be more frequently observed in Europe than in the United States. We discussed below the diagnostic criteria of RCDI and RCDII, and the possible factors underlying the more severe expression of celiac disease in Europe.