The role of different laser energy densities used in photodynamic therapy in the reparation of radiation ulcers caused by X-ray exposure in a dose of 80 Gy was studied. Tissue reparation manifested differently at different laser energy densities. After photodynamic therapy at energy density of 0.1 J/cm2 the rate of healing was notably higher during early periods. After exposure at 5 and 40 J/cm2 acceleration of ulcer healing was observed 14 and more days after the treatment, indicating the emergence of another mechanism of photodynamic therapy effect. Laser energy density of 5 J/cm2 was the most effective for maximally complete healing of radiation ulcers.