The aim of this experimental study was to evaluate the effect of bovine lactoferrin (bLF)-loaded gelatin microspheres (GM) used in combination with anorganic bovine bone on bone regeneration in surgically created bone defects around tooth implants. Twenty-four uniform bone defects were created in the frontal bone via an extraoral approach in 12 domestic pigs. Twenty-four implants were placed at the center of the defects. In eight animals one of these defects was filled with 0.3 mL anorganic bovine bone while the other was left empty. In four animals, all defects were filled with 3 mg/defect bLF-loaded GM and anorganic bovine bone. All the defects were covered with collagen membranes. All animals were sacrificed after 10 weeks of healing, and the implants with the surrounding bone defects were removed en bloc. Undecalcified sections were prepared for histomorphometric analysis. The mean total area of hard tissue was 26.9 +/- 6.0% in the empty defect group, 31.8 +/- 8.4% in the graft group, and 47.6 +/- 5.0% in the lactoferrin group (P < 0.001). The mean area of newly formed bone was 26.9 +/- 6.0% in the empty defect group, 22.4 +/- 8.2% in the graft group, and 46.1 +/- 5.1% in the lactoferrin group (P < 0.001). The mean residual graft area was 9.4 +/- 3.2% in the graft group and 1.5 +/- 0.6% in the lactoferrin group (P < 0.001). The mean proportion of bone-implant contact in the defect region was 21.9 +/- 8.4% in the empty defect group, 26.9 +/- 10.1% in the graft group and 29.9 +/- 10.3% in the lactoferrin group (P = 0.143). These data indicate that a combination of 3 mg bLF-loaded GM and bovine-derived HA promotes bone regeneration in defects around implants.