Lesions of the ureters and the bladder are represented with a relatively high portion of 40% within all gynaecological and obstetrical cases under expert opinion in the Central Office for Medical Expert Opinion. The so far mostly practisized judgement as an operational risk could not generally be consented. It is therefore that the Central Office for Medical Expert Opinion elaborated the directive No. 9: "Medical expert opinion of urological complications connected to gynaecological operations". The directive first of all means to coordinate the work within the expert opinion commissions at district level; it furtheron motivates the operator to think over his mode of action. Experiences from expert opinion result in perceiving the following main points: Even in technically simple operations the operator must know the course of the ureter; 2. if its course is not clear it must be made visible dependent on the operational situation in each case; 3. the preoperative methods of urological diagnosis have to be appropriate to the intended operation; 4. even in smallest grounds for suspicion of a lesion or complication a consequent control is necessary; a detailed documentation of the operational course is needed for various reasons; 6. the correction of lesions of the ureters and the bladder requires experience and operational ability. Because of possible grave damages to the woman the operator must be conscious of the limits of his ability. Details are demonstrated by examples of the Central Office for Medical Expert Opinion.