OBJECTIVES: Bisphosphonates are effective in reducing the risk of fractures and are used to prevent and treat osteoporosis.  Between 2000 and 2007, new bisphosphonate chemicals and formulations were introduced into Canada, and new evidence and practice guidelines emerged. This analysis provides insight into bisphosphonate use among seniors during this time period.   METHODS: Claims level data from the National Prescription Drug Utilization Information System (NPDUIS) Database were analyzed for seniors on public drug programs in six Canadian provinces between 2001-2002 and 2006-2007. The analysis looked at trends in bisphosphonates use by age and sex, by chemical, and by formulation (daily and weekly therapy). The analysis also looked at the medication possession ratio (MPR) for bisphosphonate users, a surrogate measure for compliance with therapy. RESULTS: The age–sex standardized rate of bisphosphonate use across all provinces increased from 8.9% in 2001–2002 to 12.9% in 2006–2007. The rate of use among females (20.4%) was more than six times the rate of use among males (3.3%). In 2006-2007, alendronate had the highest rate of use, at 5.9%, followed by etidronate at 4.9% and risedronate at 2.9%. There was a significant shift from the use of daily to the use of weekly therapy. The rate of use of weekly therapy increased from 0.1% to 8.4%, while use of daily therapy dropped from 9.3% to 5.3%. The surrogate measure for compliance showed little difference between patients on daily and weekly therapy. CONCLUSIONS: This analysis provides insight into how the introduction of new chemicals and dosage formulations affected bisphosphonate use among seniors between 2001-2002 and 2006-2007. There was a significant shift to the use of newer chemicals and weekly therapies. There was little difference in compliance between daily and weekly bisphosphonate users.