Injuries pose a threat to health and well-being and are a major source of medical spending in the United States for children and youth 0 to 21 years of age. This study provides national estimates of the incidence of fatal and nonfatal childhood injuries and comprehensive cost estimates by age, gender, race, family income, metropolitan residence, and place of incident. Eight years of National Health Interview Survey data (1987 to 1994) were used to estimate nonfatal injury incidence rates among children and youth 21 years of age and younger. The survey documents all medically attended or temporarily disabling injuries within the 2 weeks before the interview. Injuries were defined as diagnoses 800-995 in the International Classification of Diseases, Ninth Revision, excluding late effects cases. Fatality counts came from 1994 Vital Statistics. Estimates of the costs of injuries (1994 US dollars) included medical spending, lost future work, and lost quality of life. Medical payments included spending on hospital and professional services, rehabilitation, prescriptions, home health care, and medical equipment. Lost future work and lost quality of life consisted of the present value of work that children will be unable to do as adults if they are killed or permanently disabled combined with the pain and suffering that children and their families experience because of the injury. Cost estimates excluded parental income losses from work missed, property damage, legal costs, and insurance claims-adjustment costs related to permanent disability and death. INCIDENCE. A total of 3,073 injury episodes for 3,058 children were obtained from 8 years of National Health Interview Survey data. This represents 20.6 million children in the United States who were injured each year, or approximately 25 per 100 children. This translates to 56,000 nonfatal injury episodes each day that require medical attention or limit children's activity. For fatal injuries, the rate was 38 children per 100,000. The nonfatal injury rate for males (mean: 30; 95% confidence interval [CI]: 29,31) was higher than the rate for females (mean: 20; 95% CI: 19,21); the fatal injury rate for males was more than twice that of females. Injury rates increased with age. Children 0 to 9 years of age had the lowest rate of nonfatal injury. Rates for nonfatal injury among children 0 to 4 years of age were lower (mean: 20; 95% CI: 18,21) than those for the 5 to 9 age group (mean: 22; 95% CI: 20, 23). However, the rate for fatal injuries (21 per 100,000) among the 0 to 4 age group was higher than the 5 to 9 age group (9 per 100,000). Nonfatal injury rates for children 10 years of age and older were higher, with the highest estimated injury rates in late adolescence (15-19 years; mean: 31; 95% CI: 29,33). Nonfatal injuries occurred at higher rates among white children (mean: 27; 95% CI: 26,28) than black children (mean: 19; 95% CI: 17,21) or children from other racial backgrounds (mean: 13; 95% CI: 10,16). The reverse was true for fatal injuries, with higher fatality rates among black children (59 per 100,000). Children in families with incomes under $5,000 had the highest rate of nonfatal injury (mean: 31; 95% CI: 27,35), followed by those in the $35,000 to $49,999 income range (mean: 25; 95% CI: 23,27). The rate of nonfatal injuries in the other income brackets were fairly similar, with those in the highest income bracket having the lowest rate (mean: 14; 95% CI: 13,15). Fatality rates by family income were not available. The nonfatal injury rate in nonmetropolitan areas (mean: 10; 95% CI: 9,11) was higher than in metropolitan areas (mean: 8; 95% CI: 7,8); the same was true for fatal injury rates (33 per 100,000 in nonmetropolitan areas vs 25 in metropolitan areas). Males consistently had higher injury rates than females across all places of injury. Youth 15 years of age and older had higher rates for injuries that occur on the public roads, in recreatio