The basis for a rational diagnostic work-up of urinary tract infections is a detailed history and a maximally standardised examination of the urine, with test strips measuring, measurement of specific density, microscopic examination of the sediment, and determination of the bacterial count in the urine employing dipstick procedures are recommended for use in the doctor's office. Isolation and identification of pathogens and the preparation of an antibiogram require a special knowledge of microbiological techniques. A requirement for the evaluation of the urine and its constituents is a knowledge of how the urine was collected; we recommend spontaneously passed urine in men and young children, and catheter urine in the case of women. Chronic inflammation of the male adnexa and chronic recurrent urinary tract infections requires radiological studies by the urologist, including a urogram, a urethrocystogram, a miction cystogram, urethropyelography and ultrasonography. Occasionally, nuclear-medical investigations and angiography or computed tomography may be necessary to obtain further clarification. In the case of outflow obstructions in the region of the lower urinary tract or urge or stress incontinence, uroflowmetry and cystometry should be performed. With the aid of this "stepwise diagnostic evaluation", both optimal clarification of the urinary tract infection and a saving of costs are possible.