Introduction: Important parameters in osteoradionecrosis (ORN) are the direct damage of osteocyte cells and vascular fibrosis. Objectives: Microscopic visualization of early, sub-clinical radiation induced degenerations. Materials and methods: Bone samples from the lower jaw: - sound bone samples, mostly from orthodontic surgery (n=10 patients); - samples with manifest ORN (n=12 patients). - 36 Gy pre-surgery, radio(chemo)therapy, samples obtained 2 -3 weeks post radiation (n=9); - 60 - 70 Gy irradiation, no evidence for ORN (12 months post-irradiation; n = 9 patients); All samples were inspected with confocal laser scanning microscopy (CLSM). For additional conventional light microscopy the intact DNA was fluorescent labeled with bisbenzimide. Comparing studies with the different microscopic techniques were carried out with thin sections (Donath sawing grinding technique) of the Technovit embedded samples. Results: In conventional microscopy all irradiated bone samples showed areas with partial to total loss of vital osteocytes. This radiation damage was observed also after 36 Gy and short interval before surgery. CLSM images additionally showed micro-morphological modifications of the lamellar structure: early loss of lamellar contours (36 Gy), progressive loss of contours (60 - 70 Gy), up to totally irregular lamella (IORN). Conclusion: The observed loss of vitality of the osteocytes confirms existing studies. Additional CLSM evidence for early radiation damages are the effects on the lamellar structure of the bone samples.