The aim of this study was to investigate the relationship between vitamin D and bone mineral density in newly diagnosed multiple sclerosis (MS) and to compare results with data from healthy controls. A total of 60 subjects, including 30 patients with MS, newly diagnosed and untreated (18 females, 12 males, at 18-40 years of age) and 30 healthy controls (20 female, 10 male) were enrolled in this study. Bone mineral density (BMD) of the lumbar spine and left femoral neck region were measured by dual-energy X-ray absorptiometry (DEXA). Serum levels of 25-hydroxyvitamin D (25OHD) were measured by chemiluminescence microparticle immunoassay (CMIA) on the Architect-i2000(A (R)) (Abbott) system. 25OHD levels of MS patients were significantly lower than in controls. 25OHD levels were 27.2 +/- A 14.1 ng/ml in MS patients and 42.6 +/- A 8.8 ng/ml in controls (p = 0.001). Twenty-six (86.6 %) of our patients had a reduced BMD in lumbar spine or femoral neck region; of these 24 patients (80 %) had osteopenia and 2 patients (6.6 %) had osteoporosis. Interestingly, there was no significant correlation between 25OHD and BMD in lumbar spine and femoral neck region (r = 0.454, p = 0,074; r = 0.636, p = 0.082). Interestingly, a significant reduction of bone density in female MS patients was observed. In our study, 25OHD deficiency and lower BMD appeared in newly diagnosed multiple sclerosis. This is compatible with shared etiologic or pathogenic factors in MS and osteopenia/osteoporosis, and calls for an active approach to optimize bone health in early stages of MS.