Objective To explore the risk of osteoporosis in elderly males with obstructive sleep apnea syndrome (OSAS).Methods From January 2015 to October 2017,623 male patients diagnosed with OSAS were collected from the sleep centers of 6 tertiary hospitals in Beijing and Gansu Province, and then divided into osteoporosis risk group (n=302) and control group (n=321) according to the results of One-Minute Risk Osteoporosis Test of International Osteoporosis Foundation. All patients were followed up regularly, and the follow-up endpoint was occurrence of risk of developing osteoporosis. SPSS statistics 25.0 was used for data analysis. Student′s t test, Mann-Whitney U test, or Chi-square test was employed for intergroup comparison. Cox regression analysis was applied to analyze risk factors for the development of osteoporosis in elderly OSAS males. Results Out of 623 male OSAS patients, 48.5% (302/623) were screened for osteoporosis risk. Compared with the control group, the osteoporosis risk group was older and had significantly lower diastolic blood pressure, smaller waist circumference, larger smoking ratio, lower average pulse oxygen saturation in sleep parameters, lower levels of triglyceride, uric acid, C-reactive protein, red blood cell count and haemoglobin level, and the incidences of carotid atherosclerosis and chronic obstructive pulmonary disease when compared with the control group (P<0.05). Cox proportional risk regression analysis showed that during a median follow-up period of 55 months, age (HR=1.029,95%CI 1.013-1.045) and carotid atherosclerosis history (HR=1.547,95%CI 1.157-2.068) were independent risk factors for the risk of osteoporosis in older males with OSAS, while larger waist circumference (HR=0.983,95%CI 0.976-0.990) and mean pulse oxygen saturation (HR=0.941,95%CI 0.904-0.979) were protective factors (P<0.05). Conclusion OSAS patients are prone to secondary osteoporosis, especially for the male OSAS patients with senior age and history of carotid atherosclerosis. Larger waist circumference and higher mean pulse oxygen saturation are protective factors for the risk of osteoporosis.