OBJECTIVES Eight million women and two million men are afflicted with osteoporosis in the United States. There are additional 34 million people exhibiting low bone mass at risk for the development of osteoporosis. The purpose of this study was to describe the drug utilization and spending trends for bisphosphonate and other alternative osteoporosis medications in the Medicaid program. METHODS Using a retrospective and descriptive study, Medicaid pharmacy claims data extracted from the Center for Medicare & Medicaid Services were analyzed from 1991 to 2007 regarding quarterly number of prescriptions, units usage, reimbursement amount, and reimbursement per prescription for the oral bisphosphonates, injectable bisphosphonates, and alternative osteoporosis medications. Drugs were identified using their respective national drug codes (NDC). RESULTS Risedronate accounted for 27% of all bisphosphonates prescriptions while alendronate accounted for the vast majority of bisphosphonate prescriptions with approximately 70% of the market over the 1991-2007 timeframe. Both alendronate and risedronate together accounted for approximately 92% of all reimbursements for both oral and injectable bisphosphonates during the study period. Alendronate's market share, as measured by total reimbursement, has been steadily declining from third quarter of 2004 to the third quarter of 2007, accounting for approximately 57% of total reimbursements, contrary to the roughly 83% of all reimbursements from the fourth quarter of 1996 to the second quarter of 2004. CONCLUSIONS Market share for the leading brand drugs has steadily declined with the introduction of generic competition as measured by overall utilization and total reimbursement, such as risedronate competing with alendronate in the bisphosphonate market and raloxifene competing with calcitonin-salmon in the alternative osteoporosis market. Examination of the Medicaid data also revealed a strident market shift in utilization following the fourth quarter of 2005, resulting from the switching of dual eligibles from Medicaid to Medicare Part D.