Measurements have been made in the rat femur in vivo and ex vivo by using an asymmetric spin echo technique of T2(1), the susceptibility contribution to T2*. The trabecular spacing in this study in rat bone is considerably less than in previous studies in the human. A significant increase in T2(1) was seen in vivo 3 mm proximal to the growth plate with ovariectomy (a model of osteopenia), from 8.1 +/- 0.7 to 10.0 +/- 0.6 ms. Parallel changes in trabecular bone mineral density measured by quantitative computed tomography were found. T2(1) was higher in living bones than in the same bones measured post mortem.