Marfan syndrome (MFS), a rare genetic disease, has a prevalence of 6.5 in 100,000. Studies show that patients with MFS have reduced areal bone mineral density (BMD) compared with non-MFS individuals. We have previously shown that patients with MFS have reduced volumetric BMD and compromised trabecular and cortical bone microarchitecture. The present study was a registry-based, nationwide, population-based, cohort study using register data, aimed to evaluate fracture risk and fracture rates in MFS. We included 406 (196 women) patients with MFS through the Danish National Patient Register and 40,724 (19,327 women) persons, randomly selected and matched from the Civil Registry System. A total of 21.9% of the MFS and 18.9% of the reference population had experienced at least one fracture from 1995 to 2018. The fracture incidence rate was 27.5 per 1000 person-years in the MFS cohort (highest in young men and old women with MFS), and 20.3 per 1000 person-years in the reference population. The overall incidence rate ratio between the MFS and the reference population was 1.35 (95% confidence interval [CI ] 1.18–1.55) for all fractures. When evaluating the risk of being registered with an osteoporosis diagnosis in the Danish National Patient Register, starting relevant treatment for osteoporosis or experiencing a hip or spine fracture, 10.3% of the MFS cohort and 3.3% of the reference population could be classified as being osteoporotic. The between-group subhazard ratio was 3.97 (95% CI 2.56–6.25). Patients with MFS started treatment with an antiosteoporotic drug at a younger age than the reference population (57 [interquartile range 55–67] versus 71 [63–73]) years. The life expectancy in MFS is increasing, resulting in more patients facing diseases that are related to old age, such as age-related bone loss and increased risk of fractures. Our data suggest that bone health and fracture prevention needs to be part of the standard care for patients with MFS.