In 30 cases coming to autopsy more or less cloudy swelling was to be observed in the kidney. This reaction varied from a very mild swelling and granular degeneration of the tubules of the cortex to a decided parenchymatous degeneration with loss of nuclear structure and erosion of some of the cells lining the tubules. The convoluted tubules were always most markedly involved. Occasionally this tubular degeneration was accompanied by a desquamation of the lining cells of the glomerular capsules. We were, however, unable to recognize an acute inflammatory reaction in the interstitial tissue or in the glomeruli in any of the cases, except the one which had developed a streptococcus bacteriæmia as a sequel to an otitis media. The kidney lesion reminded one very much of the toxic lesion which is observed in the kidney in typhoid fever. Differing, however, from the latter there was a variable congestion of the fine vessels associated with the cyanosis which was present in a certain percentage of these cases. At times the kidneys were quite wet with blood from the venous engorgement. The lesions in the kidney were of a toxic type and did not resemble reactions following the presence of the bacteria in the stroma of the organ. In the majority of instances in other diseases where bacteria themselves locate in tissues we are able to recognize focal lesions of acute necrosis or inflammation. In epidemic influenza where a variety of micro-organisms within the lung are able to reach distant structures in a bacteriæmia, we would, because of their type, expect to find inflammatory reactions of a definite kind. The absence of such reactions is very suggestive that the bacteria do not commonly localize in the kidney, but that their toxins alone affect it during its elimination. We have also entirely missed the finding of any vascular lesions in the renal system. Neither degeneration nor inflammatory reactions of any of the coats of the blood vessels could be distinguished. The partial incapacity on the part of the kidneys must, therefore, be viewed as a complication resulting from the effect of a diffusible toxin reaching them by the blood stream. The damage performed in this manner may be quite extensive upon the secreting tissues of the tubules leading to an increased or decreased output of the urinary constituents. Because of the nature of the lesion, it is probable that the kidney damage incurred during the acute epidemic influenza is only temporary and not permanent. Tubular degeneration is readily repaired, and in the absence of an inflammatory reaction in the interstitial tissue or the glomeruli avoids the development of a permanent mark or derangement in the system. This is as we find it in typhoid fever.