Objectives: To measure the early adoption of bone density testing and examine the association between older age and such testing., Design: Retrospective study of Medicare administrative claims., Setting: Five states and six urban regions in the United States., Participants: Female Medicare recipients aged 66 to 90., Measurements: Bone density testing in women without prior osteoporosis or fracture (osteoporosis screening) was evaluated. The association between age and osteoporosis screening was then examined while controlling for other demographic and health factors., Results: Of 43,802 women eligible for osteoporosis screening, 22.9% were tested between 1999 and 2001, the first 3 full years of Medicare coverage. Receipt of bone density tests decreased with increasing age, from 27.2% of women aged 66 to 70 to fewer than 10% of women aged 86 to 90. After adjustment for race, comorbidity, fracture risk, and socioeconomic factors, bone density testing decreased significantly with each age category, so that women aged 71 to 75 were slightly less likely than (adjusted odds ratio (AOR) =0.91, 95% confidence interval (CI) =0.86-0.96), women aged 76 to 80 were less likely than (AOR =0.71, 95% CI =0.67-0.76), and women aged 81 to 85 were half as likely as (AOR =0.50, 95% CI =0.46-0.55) women aged 66 to 70 to receive a bone density test., Conclusion: In the 3 years after Medicare reimbursement for osteoporosis screening began, adoption of bone density testing was lowest in women in age groups at highest fracture risk.