The present study described the histologic findings of 2 implants and surrounding tissues retrieved from human irradiated bone. For the treatment of a malignant tumor, 50 Gy of irradiation after implant placement and 60 Gy of irradiation before implant placement were provided for patients 1 and 2, respectively. In patient 1, the implant and surrounding tissues were removed from the frontal bone 24 months after implant placement because of the patient's death from a tumor recurrence. In patient 2, the implant and surrounding tissues were removed from a maxillectomy site 26 months after implant placement because of tumor recurrence. In each patient, new bone formation surrounding the implants was observed. The ratio of direct bone-implant contact along the threaded implant surface was 61.3% in patient 1 and 69.0% in patient 2. The ratio of the area occupied by mineralized bone in each thread was 75.8% in patient 1 and 81.2% in patient 2. These results indicate the potential of irradiated bone to achieve osseointegration of titanium implants. Keywords: histologic study, irradiation, osseointegrated implant