Celiac disease is an autoimmune disorder of the small intestine that occurs in genetically predisposed people of all ages starting in infancy. Symptoms include chronic diarrhea, failure to thrive, and fatigue. Increasingly, diagnoses are being made in asymptomatic persons as a result of increased screening. Serological blood tests are the first-line test to make the diagnosis. Antibody blood tests are highly specific and sensitive. Historically, celiac disease was thought to be rare, but the diagnosis has dramatically increased in the last 20 years.