This communication is presented with a twofold purpose: (1) to draw attention to the danger of urinary tract infection from retained bladder urine, and (2) to discuss briefly several conditions in which retention is frequently encountered. Stasis of urine above the level of the bladder will not be considered. THE CAUSE OF "CATHETER" CYSTITIS There is an accepted belief that catheterization of the urethra is a chief cause of urinary tract infections, and that these frequently result despite employment of the most painstaking technic. This belief I hold to be not truly in accord with actual conditions. It has always been a surprising feature, to me, that the observance of rigid asepsis seemingly exerts only moderate influence in diminishing the number of such infections. Another curious fact is that patients catheterized by well-trained nurses suffer from cystitis, while urologists continue to pass catheters and cystoscopes with impunity. Further, if gentle