We investigated whether four commonly used dual-energy X-ray absorptiometry (DXA) scanners (DPX, DPX-L,and Prodigy by GE Lunar, and Delphi-A by Hologic) could classify identical subjects as osteopenic or osteoporotic using the T-score for bone mineral density in four regions of interest: PA spine (L1-L4), femur (total), forearm (total),and 33% radius in 77 adults (38 females) free of treatment for bone metabolic disease (age range 20-81 yr). There were no significant differences between T-score means for posterior-anterior spine by DPX, DPX-L, and Prodigy, but they were higher than the mean T-score by Delphi-A (p < 0.05). Prodigy gave the lowest and DPX and Delphi-A gave the highest T-score for 33% radius (p < 0.05). No subject was classified as osteoporotic in the femur region by the four scanners, although other classifications varied by region and scanner. No two scanners classified subjects identically for osteopenia in any of the four regions. These results indicate that classification of bone density in individual subjects using T-scores varies by different DXA scanners, even the scanners were made by the same manufacturer.