The pediatric Septi-Chek blood culture system is a biphasic system that uses a 20-ml bottle of brain-heart infusion broth. We compared this system with a supplemented peptone broth tube (Vacutainer) for the recovery of aerobic organisms from blood cultures obtained from patients in a pediatric hospital. Blood specimens for culture were drawn into transport tubes containing sodium polyanetholsulfonate (SPS), and equal volumes were allocated into a Septi-Chek bottle and a Vacutainer tube which was vented for the first day of incubation. A total of 4828 blood culture sets was included, from which 243 probable pathogens were recovered, including 211 in the Septi-Chek system and 204 from the Vacutainer tube. There were no significant differences in the recovery of individual pathogens. The mean time to initial detection of pathogens was comparable in the two systems, but the mean time to growth on solid media for pathogens recovered in both systems was shorter with Septi-Chek (37.2 hr compared with 45.5 hr, p < 0.001). The pediatric Septi-Chek system is comparable with a vented Vacutainer tube for the recovery of aerobic pathogens, and its use facilitates the early identification and susceptibility testing of bloodstream pathogens.