Over a period of 5 1/2 years 305 infants less than 60 days of age with temperatures greater than or equal to 100.4 degrees F (38.0 degrees C) were evaluated for sepsis. Of these 20.6% of the infants had significant diseases although only 3.6% had bacteremia. Neither the age of the child (above or below 30 days of age) nor the height of the fever helped to identify infants with bacteremia. A white blood cell count of greater than 15,000/mm3 was useful in identifying bacteremic infants over 30 days of age only. The differential white blood cell count was not helpful in distinguishing between bacteremic and nonbacteremic infants. The appearance of the infant was the most significant predictor (P less than 0.001) of bacteremia in this age group. Infants between 30 and 60 days of age who both appeared ill and had white blood cell counts greater than or equal to 15,000/mm3 had a 27.3% chance of having bacteremia.