Urinary incontinence is becoming an increasingly dominant condition in daily urological and gynaecological practice, although the total number of patients suffering from the different forms ofincontinence remains unclear. An estimated figure for The Netherlands, with a population of 14 500000, has been given as between 500000 and 600000 patients, showing that approximately 4 % of the total population suffer from this condition, the majority being female. The impact ofthis number is tremendous, not only regarding health care costs, but even more with regard to the psycho-social consequences. It is obvious that continuing efforts must be made to under stand more fully the different forms of urinary incontinence. An exact diagnosis is the first step necessary for adequate therapy. We all know how disastrous it can be to institute inappropriate treatment as a consequence of misunderstanding the proper aetiology in each individual case. What has happened in the past 15 years? During that time we have developed sophisticated machinery to diagnose in more detail the exact ori gin of each type of urinary incontinence, and on entering a urodynamic laboratory, one is struck by the complexity of measuring equipment. But how reliable are all these measurements and how can they be translated into an effective therapy? This still remains one ofthe major problems, although continuing progress has been made and will be made by the research work of many experts in the field of urinary incontinence."