Records of 13,775 consecutive autopsies were reviewed to determine the incidence of renal and urinary tract abnormalities. A total of 636 abnormalities were found in 427 autopsies, with an overall frequency of 4.6 percent and 9.5 percent in males under eighteen years old. The kidney was involved in 45.1 percent, ureters 29.1 percent, renal vessels 12.4 percent, urethra 5.3 percent, bladder 4.8 percent, and fistulas 3.3 percent. We conclude: (1) Although it is difficult to assess accurate incidence rates of renal and urinary tract abnormalities, this study notes the frequency of these abnormalities in autopsies. (2) The markedly higher incidence in the younger age group indicates the high mortality of many of these anomalies. (3) Over 85 percent of abnormalities are in the upper urinary tract, which are more likely to produce end-stage renal disease and a higher mortality. (4) These observations indicate the importance of further research to establish methodology for early detection of congenital abnormalities of the kidney and urinary tract.