Nonresponse or relapse of symptoms is common in patients with celiac disease treated with gluten free diet. Refractory sprue (RS) is defined as initial or subsequent failure of a strict gluten-free diet to restore normal intestinal architecture and function in patients who have celiac-like enteropathy. The aims of this study were: 1) to identify causes of persistent symptoms in patients referred with presumed diagnosis of nonresponsive celiac disease (NCD); and 2) to characterize patients with true RS.