A BACTEC aerobic nonradiometric medium, PEDS Plus, designed for diagnosis of pediatric bacteremia was evaluated in three hospital centers. Equivalent blood volumes (up to 5 ml) were inoculated into and incubated in BACTEC NR-6A (6A) and PEDS Plus broths. Among 4,581 compliant sets, 289 clinically significant organisms, representing more than 20 bacterial and two Candida species, were isolated. One hundred eighty-one isolates were recovered in both bottles, 75 in PEDS Plus only, and 33 in 6A only (P less than 0.001). Time to detection when both bottles were positive was the same for 129 isolates, detection with PEDS Plus was earlier for 39, and detection with 6A was earlier for 13 (P less than 0.005). Staphylococcus aureus was recovered significantly more often in PEDS Plus than in 6A (P less than 0.01), and more coagulase-negative staphylococci and pediatric pathogens (pneumococci, Haemophilus influenzae, and Streptococcus agalactiae) were recovered in PEDS Plus than in 6A. Coagulase-negative staphylococci and H. influenzae were detected significantly earlier in PEDS Plus (P less than 0.05 and less than 0.01, respectively). When the eight species of the family Enterobacteriaceae isolated were considered together, recovery in PEDS Plus was better than in 6A (P less than 0.05). For 66 of the 143 isolates from patients known to be on antimicrobial therapy at the time blood was drawn, PEDS Plus was superior to 6A. In 45 cases, organisms were isolated from PEDS Plus only (P less than 0.001) and in 21 cases they were isolated from PEDS Plus before 6A (P less than 0.01). PEDS Plus broth aids diagnosis of pediatric bacteremia by increasing recovery of etiologic agents and decreasing the time required for detection.