The aim of this study was to describe epidemiology of male osteoporosis in Denmark. In this nationwide registry-based cohort study, we identified men with osteoporosis, 50years or older, residing in Denmark, during the years 1996-2018. Osteoporosis was defined as one of the following: a hospital diagnosis of osteoporosis; a hospital diagnosis of osteoporosis fracture; or an outpatient dispensing of an anti-osteoporosis medication. We reported annual incidence and prevalence and described the distribution of fractures, comorbidities, socioeconomic status, and initiation of anti-osteoporosis therapy among men with osteoporosis. Selected characteristics were also described among men without osteoporosis of similar age. There were 171,186 men fulfilling the study criteria for osteoporosis. The overall age-standardized incidence rate of osteoporosis was 8.6 per 1000 person-years (95% confidence interval (CI), 8.5-8.6), varying between 7.7 and 9.7, while the prevalence increased from 4.3% (95% CI, 4.2-4.3) to 7.1% (95% CI, 7.0-7.1) during the 22-year period. The remaining-lifetime risk of developing osteoporosis after age of 50years was close to 30%. The proportion of men initiating anti-osteoporosis treatment within 1year of diagnosis increased from 6.9% to 29.8%. Men with osteoporosis had more comorbidities and redeemed more medication than did men without osteoporosis of similar age. Osteoporosis among men may be undertreated despite increasing treatment initiation.