OBJECTIVE: The US national cost of osteoporosis was estimated at $6.1 billion in 1984 and $20 billion in 1998. Current literature suggests that prescribing of secondary preventive therapy has not been maximized which would reduce the occurrence and cost of secondary fracture. Additionally, patient acceptance of treatment alternatives has not been maximized due to the administration complexity and potential side effects of bisphosphonates. Alternative agents with osteoporotic benefits may be used in some women to increase patient adherence. Additionally, patient acceptance and adherence may increase after an osteoporotic incident (fracture or vertebral collapse). The purpose of this study was to assess compliance rates through refill adherence with bisphosphonates vs. alternative osteoporotic treatments (estrogen replacement therapy, salmon calcitonin, or raloxifene) in primary and secondary prevention among women. METHODS: Members of a Southeastern Michigan managed care organization were retrospectively identified with pharmacy claims by those receiving bisphosphonates, estrogen replacement therapy, salmon calcitonin or raloxifene. Women > 45 years of age as of 1/1/2001 were cross-referenced with medical claims for a diagnosis of non-traumatic fracture by CPT and ICD-9 codes between 1/1/1996 to 4/30/2001. Women with a history of fracture with treatment were classified as having secondary treatment prevention; women without a history were classified as primary treatment prevention. RESULTS: Mean adherence rates were 76.32% (±39.12) in the primary prevention population (n=653) and 84.91% (±31.08) in the secondary prevention population (n=114). The bisphosphonate treatment group's (n=78) mean adherence rate was 77.69% (±33.92); the alternative treatment group's (n=689) rate was 83.86% (±38.62). CONCLUSIONS: Treatment associated with secondary prevention and involving alternative treatments had the highest adherence rates. Patient adherence and acceptance should be considered in determining osteoporosis treatment guidelines to ensure those most likely to benefit receive proper treatment.