Abstract Recent reports of large series of cesarean sections performed at various maternity centers throughout the country have, almost without exception, presented maternal mortality rates reduced to almost the ideal minimum. While these reports are admirable and the results are enviable, unfortunately, they tend to create a false impression, especially among the less experienced members of the profession—that cesarean section has become a procedure with minimal risk to the patient which does not need the same serious consideration accorded to other major surgical procedures. The reduction of maternal mortality has been brought about by many advances in obstetrie care. Among the most important are: (1) more thorough training of obstetricians; (2) the increased percentage of deliveries performed by obstetricians; (3) requirements for competent consultation for all obstetric complications; (4) blood banks; (5) antibiotic and chemotherapeutic drugs; and (6) improved obstetric anesthesia. As a result of these improvements in obstetric care, deaths associated with cesarean section have become so rare that no one individual nor even any one hospital staff has enough experience to realize that preventable cesarean section deaths still occur frequently enough to constitute an important problem at the present time. This fact can be appreciated only by a critical review of the deaths which occur among a large section of the population, such as a metropolitan area. This presentation, therefore, is an analysis of the maternal deaths associated with the cesarean sections which were performed in the City of Philadelphia from Jan. 1, 1938, to Dec. 31. 1953. The information was obtained from reports submitted to the Committee on Maternal Welfare of the Philadelphia County Medical Society. For comparative purposes, this study will be divided into two eight-year periods, 1938–1945 and 1945–1953. This division occurred at a natural point because during the second eight-year period an easily obtained and adequate supply of blood from banks was available even in the smaller hospitals. Also during this later period the obstetrician had available chemotherapeutic and antibiotic drugs covering a wide range of pathogenic organisms. A comparison of the number of deaths in each period makes it obvious that both of these advances in therapy had a great effect upon the number of fatalities.