The value of cystometry in the diagnosis of recurrent urinary incontinence is to differentiate between urge and stress incontinence. This is possible through determination of detrusor hyperactivity characterized by uninhibited detrusor contractions. Cystometry is necessary since neither history nor clinical examination can differentiate between urge and stress incontinence. Both types of incontinence are in many patients found together and factors causing stress incontinence, for instance coughing, may also cause spontaneous, uninhibited detrusor contractions. The diagnosis of detrusor hypoactivity is also important although lack of detrusor contractions is not identical to lack of contractility. In only 50% of patients are detrusor contractions present following correction of the urinary incontinence and increase of urethral resistance. In the other half of the patients, lack of detrusor contractility remains. There is evidence that a so-called micturition-stop-test may allow a prognosis in cases of lack of bladder contractility. Cystometry is, therefore, a conditio sine qua non although it only gives information concerning the function of the detrusor. Concerning the evaluation of the bladder outlet, additional radiological and urodynamic examinations are necessary.