Estimates of the excess health care costs from the exposure of children to tobacco smoke are not available in the United States. We use two nationally representative databases and current econometric techniques to estimate annual health care costs attributable to secondhand exposure by adults in the household. The point estimate closest to significance (p = .11) indicates annual smoking attributable costs equal $890 in 2003 dollars and approximately 2 percent of total annual neonatal and pediatric health care costs. Our inability to find a statistically significant effect appears driven by the negative relationship found between the child's exposure and any use/expense for the child. Unobserved caregiver characteristics are likely to be positively associated with smoking but negatively associated with children's health care utilization. This is consistent with evidence from observational studies that indicate adult smokers' lower orientation toward preventive care contributes to a decreased use of discretionary health services.