Celiac disease (CD) may be a much under recognized condition, in part because it is not considered in those patients at high risk or in clinical conditions that may be a manifestation of CD. Screening high-risk groups may reveal a higher prevalence than seen in the general population. Several diseases have been described to have an association with CD that may be greater than by chance alone. The presence of autoimmune conditions such as insulin-dependent diabetes mellitus (T1DM) or a family history of CD or dermatitis herpetiformis may increase the risk of coexisting CD. The prevalence of CD may be increased in certain patient groups, including the following: osteoporosis or low bone mass or iron-deficiency anemia. Many studies, including population-based work, suggest a prevalence of CD of 3%-7% of T1DM and 4%-10% of first-degree family members. Anemia and osteoporosis are common in patients with newly diagnosed CD. Conversely, CD is common in referral populations with those conditions but makes a relatively small contribution to the overall community prevalence of anemia or postmenopausal osteoporosis. Most screen-found patients tend to have little or no gastrointestinal symptoms. In conclusion, significant reservoirs of CD can be found in some at-risk groups, such as those with T1DM, family members, and referred patients with osteoporosis and anemia. It is not clear what impact CD has on the quality of life of these individuals.