A study of 125 titanium implants placed in irradiated bone is reported. Eighty-eight implants were placed in nonirradiated bone and 45 implants were placed in irradiated bone after hyperbaric oxygen treatment (HBO) was undertaken in 68 patients. There was an increased loss of implants in irradiated bone (38.4%) compared to nonirradiated bone (17%). None of the implants placed after HBO was lost. Low irradiation doses did not prevent implant losses. Longer intervals from the time of irradiation to implant surgery resulted in more implant losses. The highest implant losses were seen in the periorbital bone. Three-millimeter-long implants showed increased loss compared to 4-mm or longer implants. Retention of the prosthesis with bar and clips resulted in reduced implant losses, compared to the use of individual magnets or a combination of magnets and clips. Using a grading system for cutaneous reactions, irradiated skin showed increased adverse reactions during the first year after implant surgery. Adjunctive treatment with HBO reduced adverse skin reactions. Schlagwörter: hyperbaric oxygen treatment, irradiation, osseointegration, prosthetic reconstruction, titanium implants