Recently we made a determination of the incidence of syphilis in the patients seen at Duke Hospital. As a whole it was found to be 8.13 per cent. There was a marked disproportion between the white and colored patients. The incidence in white male patients was 2.7 per cent, and for the white female patients 3.2 per cent. In colored males the incidence of infection was 29 per cent and in the colored females 32 per cent. As can be seen from these figures, for the population group from which these patients were drawn, the incidence of syphilis in the colored race was roughly ten times that of the white race, and a greater incidence of syphilis was found in the females of both races. Because of this finding, we felt that a determination of the incidence of syphilis in pregnant women should be made because of its implications as a public health problem and as a problem of preventive medicine.As a basis for this study the records of 2,152 unselected patients, all pregnant women, who were admitted during the years 1930 to 1938 to the obstetric wards, both private and public, of this hospital were examined.The criteria employed for the diagnosis of syphilis consisted of either the laboratory finding of repeatedly positive blood serology and, in early seronegative syphilis, the finding of the Treponema pallidum on repeated dark-field examinations, or a definite history of syphilis for which no treatment or inadequate or insufficient treatment had been received with or without physical signs or stigmas of syphilis.Blood serologic examinations were made routinely on all the obstetric patients at the time of their first visit to the prenatal clinics or at the time of their admission to the hospital, if no prenatal examinations had been made, and also in most cases serologic examinations were again made at the time of delivery. The serologic tests used were the Wassermann and Kahn reactions.All of the patients diagnosed as having syphilis in the group on which this study was based were found to have a strongly positive Wassermann and/or Kahn reaction with the exception of 9 cases. Of these 9 serologically negative cases, 8 of the patients gave a definite history of syphilis and of having received some treatment prior to their pregnancy and 1 patient had dark-field, positive, seronegative, primary syphilis.