The problems about the value of excretory urography as a preoperative diagnostic examination in patients with benign hypertrophy of the prostate are discussed. On the basis of IVP (i.v. pyelography), renal function and absence of hematuria and/or infection in 500 consecutive patients who were to undergo prostatic surgery, it is concluded that IVP is a superfluous examination. In patients with impaired renal function (Se-creatinine > 1.5 mg%) IVP showed abnormalities in 41.3%. In patients with normal renal function and urinary tract infection IVP revealed abnormalities in 20.6%. In patients with normal renal function and microscopic hematuria IVP showed abnormalities in 19.2%. IVP should be undertaken in patients with impaired renal function (Se-creatinine > 1.5 mg%) and may be considered in patients with normal renal function with hematuria or infection.