Background & Aims: A high prevalence of osteoporosis is reported in inflammatory bowel disease (IBD), and its pathogenesis is not completely resolved. We investigated whether bone mineral density (BMD) in patients with IBD at diagnosis is lower than in population controls, and whether BMD differs between patients with Crohn's disease and those with ulcerative colitis. Methods: In 68 patients and 68 age- and gender-matched population controls, BMD of total body, spine, and hip was assessed using dual-energy x-ray absorptiometry within 6 months after establishing the diagnosis, Determinants for low BMD were assessed. Results: There were no significant differences in BMD (g/cm(2)) between patients and controls, and no significant differences in BMD between patients with either Crohn's disease or ulcerative colitis. Multivariate regression analysis showed that duration of complaints longer than 6 months before diagnosis (P = 0.041), age (P = 0.019), and body mass index less than 20 kg/m(2) (P = 0.006) significantly correlated with low BMD, Conclusions: BMD in patients with recently diagnosed IBD was not significantly decreased compared with population controls. Subsequent development of osteoporosis in patients with IBD seems to be a phenomenon related to the disease process and/or the treatment modalities of IBD.