Numerous bone graft substitutes are available as alternatives to autologous and allograft bone grafts. The use of ultraporous beta-tricalcium phosphate for cavitary bone defects in our institution was based on the hypothesis that it would have gradual but complete incorporation over several months, similar to the smooth transition seen in animal models. This retrospective, uncontrolled study reviews 24 patients who had bone grafting of a cavitary defect with ultraporous beta-tricalcium phosphate mixed with local blood. Radiographically, resorption and trabeculation increased steadily with time, with trabeculation lagging slightly behind resorption. Resorption and trabeculation were more advanced at times beyond 6 weeks in small defects (< 43 cm) compared with large defects (>/= 43 cm). The presence of peripheral radiolucency seen early around nearly all grafts disappeared in small lesions by 1 year, but still was visible in larger lesions at the latest followup. Bone renewal seems to correspond temporally with gradual replacement of graft material, but incorporation is not complete even at 1 year in large defects. Clinically, there is a low rate of complications associated with the use of ultraporous beta-tricalcium phosphate, and patients progressed to unrestricted activities of daily living and recreational activities within 3 months.