Evidence of the prevalence of celiac disease comes from serological screening studies. These have revealed that celiac disease is common, occurring in about 1 % of the population worldwide. There are some countries with higher prevalence rates such as Finland and others with lower rates, for example Germany. The disease is found in most continents and appears to be increasing. Most people with the disease are not currently diagnosed though women are diagnosed more frequently than men. The mode of presentation has changed both in children and adults with diarrhea and a malabsorption syndrome becoming less common. Abdominal pain and growth issues are major modes of presentation in children, while anemia, osteoporosis, and recognition at endoscopy performed for GERD are seen as modes of presentation in adults. Screening of at risk groups is a major mode of presentation for both adults and children.