Two successive series of invasive carcinoma of the cervix (268 and 307 patients) were treated by radiation alone between 1973 and 1977 and 1978 and 1985. The main difference between these periods was the method used to determine the definitive dose delivered by intracavitary therapy. The treatment in all cases consisted of external and intracavitary radiotherapy. Computerized dosimetry was performed in all patients with determination of dose rate, maximum and mean cumulated doses at the reference points of the rectum and bladder. The tolerance doses to the rectum and bladder previously established and represented graphically were used prospectively for the patients from 1978 to 1985, permitting better coordination of the two treatments. The graph takes into account the fractionated tolerance to external irradiation and intracavitary radiotherapy. The systematic use of this method yielded results at six years for all stages which were comparable from one series to another. Parallel to this, the improvement in the number and gravity of the complications was significant, especially for grade 2 complications (P = 0.001) and, to a lesser degree, for grade 3 and 4 complications (P = 0.04). In conclusion, the respect of tolerance doses to the critical organs close to the principal tumoral volume represents an effective method for optimizing radiotherapeutic treatment for cervical cancer.