We aimed to evaluate the impact of obstructive sleep apnea (OSA) on bone mass densities (BMD) in young people with sleep apnea. Ninety five consecutive patients, referred to our sleep clinic for sleep apnea symptoms were enrolled in the study. The study complied with the declaration of Helsinki and was approved by the local research ethics committee. All patients underwent in-laboratory polysomnography (PSG) and BMD analysis with dual-energy X-ray absorptiometry (DXA) in lumbar spine (L1–4) and total femur region. Patients with total sleep time less than 4 h, chronic renal, pulmonary, cardiac, thyroid disease, diabetes mellitus, hypertension, steroid usage and known osteoporosis were excluded from the study. Totally 85 patients with mean age of 35.7 ± 5.7 were enrolled in the study. 47 patients: normal, 33 patients: osteopenic, five patients were found osteoporotic. Osteopenic and osteoporotic patients were considered as one group in statistic tests. Mean femur neck T score and total femur T score values were higher, while mean total lumbar T scores and lumbar BMD values were less in patients with severe OSA. apnea–hypopnea index (AHI) was inversely correlated with total Lombar T scores (r = −0.250, P = 0.021) and positively correlated with Total Femur T scores (r = 0.242, P = 0.029. AHI ≥ 30 was related with 4.26-fold (95% CI 1496–12.1) increased risk of lumbar osteopenia and osteoporosis. We have found that OSA is associated with low BMD especially in lumbar region and suggest OSA to be remembered as one of the secondary causes of osteoporosis in young patient groups.