104 patients submitted to primary irradiation for cervix carcinoma were examined by means of urodynamic methods of diagnosis in order to investigate the functional changes of the lower urinary tract induced by therapy. 34 patients could be examined prior to therapy, 19 and 12 patients, respectively, were examined six and 18 months on an average after the treatment. Another group of 70 patients had retrospective check-up examinations with average intervals of five and ten years. Hydronephrosis occurred only as a late result after more than six years in 12% of the irradiated women. The incidence of residual urine, significant bacteriuria, and disturbed sensory function of the bladder was not important. All patients were incontinent two years after the irradiation; 60% of the cases of incontinence were due to the bladder and 40% to the urethra. The increase of urgency incontinence is possibly caused by a radiofibrotic reaction of the bladder, as is shown by correspondent cystometric alterations: the bladder tonicity increased, whereas the bladder capacity decreased. These alterations were only partially reversible. The stress incontinence, however, was found already before the treatment. The maximum urethral closing pressure, which often indicates incontinence due to the urethra, was not modified by the irradiation. An increased stress incontinence, probably caused by advanced age, was found only after six years or later. The problems resulting from functional changes should be taken into consideration in the course of post-therapeutic care, ie the patients concerned should be given instructions for a regular bladder training.