OBJECTIVE: To describe ED visits for influenza-like-illness (ILI) during the April-June 2009 H1N1 outbreak in US children's hospitals. DESIGN/METHODS: We used the Pediatric Health Information System (PHIS) databases of ED visits for 25 children's hospitals, using data from MMWR weeks 14-25 of 2009, with data from the corresponding weeks of 2008 as comparison. Weekly average daily census (ADC) for ILI was calculated using previously-validated ICD-9 codes for ILI. The start and end of the surge for each hospital was defined by the first and last 2 adjacent weeks with ADC of ILI at least 25% above the 2008 week's ILI ADC. For each hospital's surge period, we report surge duration; the ADC and ILI ADC relative to 2008 baseline, and ILI admit rate with non-ILI admit rate as comparison. RESULTS: Of the 25 EDs, 15 (60%) had an ILI surge during the study period. Among those with surge, the magnitude of all-patient ED surge ranged from 8.4-48.9% above 2008 baseline, and the magnitude of ILI surge ranged from 30.9-78.7% above 2008 baseline. The ILI admit rate was 2.1-8.2% among hospitals. The epidemic curves are shown for the 15 hospitals with ILI surge is shown in the Figure. CONCLUSIONS: The Spring H1N1 surge was experienced by most, but not all, children's hospital EDs. Surge magnitude varied, but the ILI acuity, reflected in admit rates, was lower than the overall acuity at nearly all hospitals.