Impact exercise can have beneficial effects on the growing skeleton. To understand what changes it promotes in the shafts and ends of weight-bearing bones, we measured the effects of impact from repetitive freefalls in growing rats. Fischer 344 female rats, 6.5 weeks old, were assigned to 1 of 3 groups (n=10 each). Controls were not dropped, while those subjected to impact were dropped from 30 cm or 60 cm. Rats in both freefall groups were dropped 10 times per day for 8 weeks. Leg bones were mechanically tested and their cross-sectional area (CSA), cross-sectional moments of inertia (CSMI), and volumetric bone mineral density (BMD) measured by peripheral quantitative computed tomography (pQCT). In the shafts of the forelimbs, but not the hindlimbs, freefall impact resulted in greater ultimate breaking force (Fu), minimum and maximum second moments of area (I_MIN and I_MAX), and CSA but not BMD. In the bone ends of the forelimb and tibial bones, trabecular BMD increased but CSA did not. Landing from 30 cm and 60 cm produced peak impact forces of 12.0 and 16.7 times the standing forefoot weight for each front leg, and 4.5 and 7.7 times the standing hind foot weight for each hind foot. Overall, freefall impact affected the forelimbs by increasing trabecular bone density in the bone ends and improving the strength at the shaft due to geometric improvements. These results indicate that adaptation to impact may occur by different mechanisms in bone end and shaft regions.