OBJECTIVES: The goal of this study was to identify the prevalence of occult bacteremia (OB) in well-appearing, previously healthy children aged 3 to 36 months who present to the emergency department (ED) with fever without source in the post-pneumococcal conjugate vaccine (PCV) era. METHODS: This was a retrospective cohort study of children presenting to an urban pediatric ED between July 1, 2004, and June 30, 2007. Children were included if they were aged 3 to 36 months, febrile, and previously healthy; had no source of infection on examination; had a blood culture drawn; and were discharged from the ED. Outcome measures were rates of OB and contaminant rates. RESULTS: A total of 8,408 children met all inclusion criteria. There were 21 true-positives, yielding an OB rate of 0.25% (95% confidence interval [CI] = 0.16% to 0.37%). There were 159 contaminant cultures yielding a contaminant rate of 1.89% (95% CI = 1.61% to 2.19%), or a ratio of 7.6 contaminants for each true-positive. There were 14 included patients who grew Streptococcus pneumoniae from the blood, for a rate of 0.17% (95% CI = 0.09% to 0.27%). CONCLUSIONS: Given the current rate of OB in the post-PCV era, it may no longer be cost-effective to send blood cultures on well-appearing, previously healthy children aged 3 to 36 months who have fever without source.