The authors analyse 123 cases of carcinoma of the uterine cervix treated by radiotherapy, with CEA radio-immuno-assay performed before treatment then each time patients are seen in follow-up. The CEA level is positive in 35 per cent of the cases with a mean value of 21 per cent for stage I, 36 per cent for stage II and 48 per cent for stage III. CEA level become negative at the end of the treatment (80%) or after (100%) when there is a complete disappearance of the tumour. The persistence of a positive level is well correlated with the abscence of sterilization, and reappearance of CEA evokes a recurrence. Preliminary results do not seem to show a prognosis value of pre-therapeutic level of CEA according to survival rate at 2 years.