We prospectively examined the utility of obtaining blood cultures through newly inserted intravenous catheters in 99 children who required both a blood culture and placement of an intravenous catheter. Two blood cultures were collected from each patient, one through a freshly inserted intravenous catheter and another through a butterfly needle at a separate venipuncture site. A standardized technique of skin preparation with povidone-iodine was used. The rate of contamination was 1.0% (95% confidence intervals, 0 to 3.0%) for each method. Ten patients had blood cultures yielding true pathogens; in five of these bacteremic children, only one of two sets of blood cultures was positive. We conclude that blood cultures can be collected through freshly placed intravenous catheters without increasing the risk of contamination. These results also raise the possibility that obtaining two blood cultures instead of a single culture may improve the detection of bacteremia in children.