OBJECTIVES: Since the 1993 estimate of the burden of osteoporosis in Canada, the population has aged and new treatment options have been introduced. The study purpose was to estimate the current burden of illness due to osteoporosis in Canadians aged 50 and over.   METHODS:   Analyses were conducted using five national administrative databases from the Canadian Institute for Health Information for the fiscal-year ending March 31 2008 (FY 2007/08). Gaps in national data were supplemented by provincial data extrapolated to national levels. Osteoporosis-related fractures of the hip, humerus, vertebra, wrist, other sites and multiple sites were identified using a combination of most responsible diagnosis and intervention codes. Fractures associated with severe trauma codes were excluded from the analysis. Costs, expressed in 2010 dollars, were calculated for osteoporosis-related hospitalizations, emergency care, same day surgeries, rehabilitation, continuing care, home care, long-term care, prescription drugs, physician visits and productivity losses.  Sensitivity analyses were conducted to measure the impact on the results of key assumptions. RESULTS: Osteoporosis-related fractures were responsible for 57,413 acute care admissions and 832,594 hospitalized days in FY 2007/08.  Acute care costs were estimated at $1.2 billion. When outpatient care, prescription drugs and indirect costs were added, the overall yearly cost of osteoporosis was over $2.3 billion for the base case analysis and as much as $3.9 billion if a proportion of Canadians were assumed to be living in long-term care facilities due to osteoporosis.  CONCLUSIONS: Osteoporosis is a chronic disease that results in a substantial economic burden to the Canadian society.