It is particularly difficult to establish a physico-technical irradiation plan for the thoracic part of an oesophagus carcinoma. This is due to the considerable modifications of the thoracic cross-section within the longitudinal axis of the radiation field. Therefore, tomographic cross-sections were made of the upper, the middle and the lower plane of the radiation field. The percentage dose distributions could be determined with a process computer (system TPS, Phillips) for different irradiation techniques and irradiation equipments. Examinations of 21 patients showed that the best dose distribution, i.e. a distribution which spares the lung and spinal marrow regions adjacent to the target volume, is obtained by an excentric moving field therapy. Furthermore, localisation and dimensions of inhomogeneities are indicated by computed tomography which makes possible to take into consideration these inhomogeneities when calculating the dose. It was found that the irradiation times can so be reduced by more than 20%. We are therefore of the opinion that it is necessary to establish individual cross-sections of the body by computed tomography when elaborating a physico-technical irradiation plan for the treatment of an oesophagus carcinoma.