Purpose: To investigate the osseous repair in epiphyseal rabbit femur defects treated with organic bovine bone (OBB) cancellous block or OBB cortical granules. Materials and Methods: Forty-eight trephined defects were made bilaterally in 30 rabbits. In 18 animals, the defects were filled with OBB cancellous block (experimental group 1) or OBB cortical granules (experimental group 2), and in 12 animals (control group), the defects on both sides were filled only with blood clot. After 30, 90, and 180 days, the femur epiphyses were collected, fixed, radiographed both digitally and conventionally, and then processed for histologic analyses. The newly formed cortical bone was measured in the histologic sections using a digital image analysis system. Results: Histologically, both experimental groups showed total or partial closure of the defects with woven bone at 30 days, whereas in the control sites, a marked migration of connective tissue into the defect was apparent. At 90 and 180 days, a similar pattern of repair was observed in the experimental groups and the control group. Quantitatively, however, no significant differences between groups (P > .05) were observed throughout the experimental period. A significant reduction in newly formed cortical bone occurred at 90 and 180 days (P .05) in all groups. Radiographically, no statistically significant differences were seen among the groups (P > .05). Conclusions: The study showed minor descriptive differences at the first healing period that were not evident at later periods and that were not shown through histomorphometry and radiographic analysis. The only significant results were related to time. Schlagwörter: bone repair, demineralized bone matrix, osteogenesis, rabbit, xenograft