Review of the bacteriology records of a University Hospital pediatric service for a 30-month period revealed 42 patients with Hemophilus influenzae type b bacteremia and 30 patients with Streptococcus pneumoniae bacteremia, all under age 10. Eighty-eight percent of the Hemophilus bacteremias and 7% of the pneumococcal bacteremias occurred in children less than 2 years of age. Hemophilus bacteremia was seen mot frequently in the first year of life, in contrast to pneumococcal bacteremia which was seen evenly throughout the first and second years of life. In all but one of the Hemophilus infections, a definite source of the bacteremia was apparent; these included CNS infection (58%), cellulitis (14%), and pneumonia (12%). In contrast, no obvious source was apparent in 37% of the pneumococcal bacteremias. When a focus for pneumococcal bacteremia was identified, otitis media and pneumonia were the most frequent diagnoses. Most of the occult pneumococcemias were transient; the results of repeat blood cultures before a treatment decision were helpful in determining the necessity for and duration of antibiotic therapy in those patients with no obvious source of infection.