Up to 1900, diverticula were almost universally a necropsy finding. Since that time, with the perfection of the cystoscope and methods of cystography, they have been observed rather frequently, and numerous urologists have published articles on the subject, each with a sizable series of case reports with operation. Therefore, it is our intention in this paper to consider certain features only, instead of attempting to put forth a comprehensive study of the diverticulum in all its aspects. The importance of diverticula is emphasized by the fact that a badly infected, poorly draining diverticulum, especially with ammoniacal urine, gives rise to subjective symptoms, namely, dysuria, pain and distress, not exceeded in severity by advanced vesical tuberculosis, carcinoma or stone. It seems to be conceded that, in the vast majority of cases, two etiologic factors are operative: (1) embryologic defects in the bladder—weakened spots—and (2) obstruction (usually at the bladder neck). Our