We investigated the bone mineral density (BMD) and prevalence of osteopenia and osteoporosis in adult celiac patients with varying disease states. In this cross-sectional study the data on the severity of celiac disease and BMD were collected from 77 celiac patients (28 newly diagnosed and 49 previously diagnosed celiac patients), and BMD results were compared with those of 157 control subjects matched for age, gender, and menopausal status. The celiac patients had significantly lower BMD than the control subjects at the lumbar spine (-6%) and femoral neck (-5%). The mean BMD did not differ significantly among celiac patients classified by severity of disease. Based on Z scores, 35% of the celiac patients and 17% of the control subjects had low BMDs for age at the lumbar spine (p = 0.005), whereas 31% of celiac patients and 16% of control subjects had Z scores of < or =-1 at the femoral neck (p = 0.01). Altogether, 26% of all celiac patients, but only 5% of control subjects, were classified as having osteoporosis (T score < or =-2.5 SD) at the lumbar spine (p = 0.03), whereas osteoporosis was rare at the femoral neck in both groups (3% vs. 1%, p = 1.00). Prevalence of osteopenia and osteoporosis was highest in newly diagnosed celiac patients and in patients with disease not in remission. A low 25-(OH)D vitamin concentration was a typical biochemical abnormality in our patients (64% of men and 71% of women). The main associated variables of low BMD were age (men), low serum vitamin D level, low body weight, and postmenopausal status (women). The present study suggests that celiac disease constitutes a risk factor for osteoporosis. This finding applies particularly to untreated and poorly treated patients.