Postoperative renal infection may occur from an infection in some other part of the urinary tract, or be first in the uropoietic system. Already existing infections of the kidney pelvis may be the source of infection for infection of the renal parenchyma. Independent of operation, renal infections occur during typhoid, attacks of tonsillitis, furunculosis, or from carbuncles and paronychiae. While any one of these causes may exist after operation and be the real etiologic factor of the renal infection, only such infections as occur as a direct result of the operation or its complications are here considered. Baisch 1 states that in healthy women the urethra is seldom the seat of pathogenic bacteria, but that in those post partum, and after operation, the urethra becomes the habitat of infectious micro-organisms, and that the number present is in direct ratio to the length of time that the woman remains in bed.