PURPOSE: This study retrospectively evaluated implant survival of 631 osseointegrated implants installed in irradiated cancer patients over a 25-year period. PATIENTS AND METHODS: The files of 107 patients followed since 1979 were evaluated. Factors influencing implant survival as oncologic treatment, radiotherapy protocols, patient and implant related elements were analyzed. RESULTS: Compared with a control group of non-irradiated patients, implant failures were higher after previous radiotherapy. High implant failures were seen after high dose radiotherapy and a long time after irradiation. All craniofacial regions were affected, but the highest implant failures were seen in frontal bone, zygoma, mandible, and nasal maxilla. Lowest implant failures were seen in oral maxilla. The use of long fixtures, fixed retention, and adjuvant hyperbaric oxygen therapy decreased implant failures. Noncontributing factors to implant survival were gender, age, smoking habits, tumor type and size, surgical oncologic treatment, and osseointegration (OI) surgery experience. CONCLUSION: Survival after cancer therapy is so high, and outcome from OI therapy so favorable that OI in the irradiated patient can be recommended. However, the OI clinician should be aware of the risks and pitfalls of treating such patients.