Most patients with bladder outlet obstruction present themselves with clear-cut symptoms, so that diagnosis is easy. There is a substantial group of patients who have vague or bizarre urinary tract symptoms and in whom the possibility of bladder outlet obstruction should be considered when no other cause for the symptoms is apparent. These patients should undergo pyelographic, cystourethroscopic, and urethrographic examination. Direct measurement of intravesical pressures during urination is valuable in diagnosing vesical outlet obstruction which is not revealed by other diagnostic methods. This procedure has also proved useful in evaluating the various methods of treatment.