In an 8-year period, 16 cases of parturitional septicemia due to the Enterobacteriaceae in the immediate postpartum period were identified that were not due to pyelonephritis. Fourteen of the 16 patients had more than 100,000 colonies per milliliter of urine of the same member of the Enterobacteriaceae as was present in the blood. Twelve of the 16 patients had concomitant endometrial cultures. In 11 patients the same isolate was recovered from urine and endometrium as had been recovered from the intravascular compartment. The data suggest an etiologic relationship between asymptomatic bacteriuria and septicemia due to the Enterobacteriaceae in which the maternal implantation site affords the principal portal of infection.