Thyroid ophthalmopathy is listed among benign disorders as the fourth indication for radiotherapy. Radiation reduces symptoms and signs of the disease in 46-93% of patients. Except for the lenses, the orbital content is resistant to the usual radiation dose of 20 Gy in 10 fractions. A number of radiotherapeutic techniques which avoid the lenses have been suggested. The testing of different techniques was performed on the same patient by using a computerized simulation of lateral alternating and crossed photon beams from a 6 MV and 18 MV linear accelerator or cobalt device. The radiation from a 6 MV linear accelerator using lateral beams angled at 5 degrees posteriori gave the best results. By this technique both lenses receive below 10% of the prescribed dose with a safety zone of 20% of the field size. Isodose distribution in clinical target volume is within the range of 10%. The described technique is recommended as it enables a successful avoidance of both lenses with a satisfactory homogeneity of dose distribution in the clinical target volume.