This study evaluated the effectiveness of a mineralized cancellous bone allograft (Puros) for the treatment of human periodontal osseous defects. Twenty patients with chronic periodontitis each contributed at least one intrabony defect. The surgical procedure consisted of flap reflection, debridement of the defect, root planing, and placement of the bone graft in the defect, followed by flap closure. Clinical and surgical measurements were taken at baseline and at the 6-month surgical reentry. The average probing depth reduction was 4.8 ± 1.3 mm and average gain in clinical attachment levels was 4.2 ± 1.5 mm; both changes were statistically significant. The average percent bone fill was 66.8% ± 26.2% and average percent defect resolution was 71.5% ± 25.5%. Mineralized cancellous bone allograft appears to be an effective material for the treatment of osseous defects in patients with chronic periodontitis.