Background: Osteoporosis often does not involve symptoms, and so the actual number of patients with osteoporosis is higher than the number of diagnosed individuals. This underdiagnosis results in a treatment gap. Objectives: To estimate the total health care resource use and costs related to osteoporosis in the Netherlands, explicitly including fractures, and to estimate the proportion of fracture costs that are linked to the treatment gap and might therefore be potentially preventable; to also formulate, on the basis of these findings, strategies to optimize osteoporosis care and treatment and reduce its related costs. Methods: In this retrospective study, data of the Achmea Health Database representing 4.2 million Dutch inhabitants were used to investigate the economic consequence of osteoporosis in the Netherlands in 2010. Specific cohorts were created to identify osteoporosis-related fractures and their costs. Besides, costs of pharmaceutical treatment regarding osteoporosis were included. Using data from the literature, the treatment gap was estimated. Sensitivity analysis was performed on the base-case results. Results: A total of 108,013 individuals with a history of fractures were included in this study. In this population, 59,193 patients were using anti-osteoporotic medication and 86,776 patients were using preventive supplements. A total number of 3,039 osteoporosis-related fractures occurred. The estimated total costs were 465 million. On the basis of data presented in the literature, the treatment gap in our study population was estimated to vary from 60% to 72%. Conclusions: The estimated total costs corrected for treatment gap were 1.15 to 1.64 billion. These results indicate room for improvement in the health care policy against osteoporosis.