Seven patients (mean age, 37.6 years; 5 women) had several weeks of gluten sensitivity (GS)-like symptoms; 2 had flu-like symptom prodromes. The 7 cases had morphologically similar biopsy specimens; all tissue fragments had uniform injury--increased lymphoplasmacytic lamina propria inflammation, moderate to complete villous flattening, numerous crypt mitoses, and markedly increased villous intraepithelial lymphocytes (IELs). All patients were diagnosed with GS and prescribed a gluten-free diet; all returned 9 to 38 weeks later questioning their diagnosis because symptoms had resolved substantially or completely. Clinical improvement was unrelated to gluten abstinence or ingestion. Repeated endoscopy and colonoscopy performed 4.1 to 16 months later showed normal mucosa in all 7 patients. Diseases other than GS can cause marked villous flattening and increased villous IELs in adults. The cause of small bowel mucosal injury is unknown. A similar non-GS-associated clinicopathologic complex, assumed to be due to a protracted viral enteritis or slow regression of a virus-induced immune reaction, occurs in children. The temporal aspects of symptom improvement and mucosal restitution in these 7 patients are similar to "acute self-limited colitis." An overly exuberant immune response to an infectious agent is possible.