The advisability of routine roentgenographic measurements of the fetal head and maternal pelvis in obstetrics needs to be reconsidered because of the known hazards of ionizing radiation. In the years 1946-1947, among 702 patients, antenatal x-ray pelvimetry was used in 38.8%, while in the years 1956-1957, antenatal pelvimetry was restricted to 7.4% of the 597 patients. In the 1946-1947 series, 2 % of the term babies were lost from conditions not related to the delivery, such as erythroblastosis and toxemia, while in the 1956-1957 series the term fetal loss was 0.8% from conditions not related to delivery. The decreased resort to x-ray pelvimetry did not increase the fetal risk. A series of 1,200 cases was analyzed in order to determine how helpful x-ray pelvimetry was in determining the need for cesarean section, and the evidence indicated that careful clinical study of the pelvis gave sufficient information in 70 to 80% of obstetric patients. Antenatal x-ray pelvimetry is therefore to be deprecated as a routine procedure, but it should not be witheld in critical situations.