A clinical investigation was undertaken to compare regeneration of osseous defects following either osseous coagulum-bone blend grafts or open debridement procedures. Seventy-five sites in 28 patients were treated by the two procedures. The average fill in the 37 intraosseous defects treated by graft procedures (initial average depth = 4.22 mm, S.D. 1.73) was 2.98 mm, S.D. 1.44. The average fill in the 38 intraosseous lesions treated by open debridement procedure (initial average depth = 3.03 mm, S.D.0.80) was 0.66 mm, S.D. 0.80. Statistical analysis showed a significant difference (P greater than 0.01) in fill patterns between the bone blend and open debridement responses in favor of graft treated sites. Therefore greater levels of osseous regeneration apparently took place in our cases following osseous coagulum-bone blend autogenous graft procedures than following open debridement procedures in all types of defects studies.