A cooperative study was taken to comparate the doses, obtained by the different institutes. The European Group had first defined the important points of the irradiated volume. This study has shown the great differencies between the doses of the institutes. First, the reference points for the surrounding structures were examined. The average of the doses at the inferior points of the Fletcher's lymphatic trapezium varies between 500 and 1 500 rads. This at the pelvic wall point is usually more important (10 or 15%). The doses at the delicate organs, the bladder and the rectum were studied in second. The average of the maximal vesical doses varies from 4 000 to 4 900 rads in the preoperative group; the average of the maximal rectal doses between 2 100 and 5 200 rads in the same group. The examination of the mean rectal dose was difficult. Every Institute has his own means of determining it. At last the size of the reference volume was considered. The 6 000 rads isodose was selected for the whole treatment. The height of this volume seems to be essentially dependent of the length of the uterine source. There seems existing some parallelism between the width and the thickness of the reference volume, but there are many differencies from an Institute to another. Now the Group has to determine a dosimetric methodology which may be transmissible.