OBJECTIVE: Each year in the U.S., particularly around holidays like July 4th, injuries occur from the use of fireworks. Most injuries can be treated in Emergency Departments, but some are serious enough to require hospitalization. This study examines admissions resulting from fireworks-related injuries and estimates the resulting hospital cost. METHODS: Cases were identified using ICD-9 diagnosis and E-codes. Hospital costs were developed based on discharge data from 59 hospitals in seven states from 2000. Cost estimates include accommodation and ancillary services, reported in 2003 US$. Charges were adjusted using a 0.61 cost-to-charge ratio and the U.S. Consumer Price Index's annual medical care component. RESULTS: Of 98 cases identified, 90% were male. Admissions occurring in July (35%), June (15%) and January (16%) accounted for two-thirds of hospitalizations. Mean age was 25 years (median: 18, range: 5-75), 40% were under 15 years. Most (78%) were admitted via the Emergency Department and 40% stayed in ICU. Principal diagnoses revealed that 41% were admitted primarily for fracture or open wound of an extremity; second or third degree burns (25%) or eye injuries (17%). Roughly, one third (34%) required amputation of a finger or thumb. No fatalities were reported. Mean length of stay was 4 days (median: 2, range: 1-41). Mean cost per stay was $15,590 (median: $7150, range: $923 - $235,213). Cumulative cost for all cases was approximately $1.4 million. At discharge 94% went home (4% with home care) and the remaining 6% were transferred to sub-acute facilities. CONCLUSIONS: Most of the fireworks-related injuries requiring hospital level of care occurred in children and teenagers. Some injuries can be potentially life altering because of amputation or loss of an eye. These results bring attention to the need for increased education, particularly prior to holidays, of children and their parents about the dangers and consequences of using fireworks.