To estimate the frequency of bacteremia in children with sickle cell hemoglobinopathies (SCHs) and to evaluate the usefulness of various findings in predicting septicemia, we reviewed the charts of 153 patients with SCH who made 326 emergency department visits in a one-year period. Ninety children were febrile (greater than 38.0 degrees C). Four children, three of whom were 2 years old or younger, were bacteremic with Streptococcus pneumoniae. A temperature greater than 40 degrees C occurred in three of the four and was more common than in those who had sterile blood cultures. Two of the five patients who were 2 years old or younger and who had the combination of a WBC count of 20,000/cu mm or more and a temperature of 39.5 degrees C or higher were bacteremic. These children were significantly more likely to have bacteremia than those with lower temperatures and WBC counts.