In the article titled “Determination of Tobacco Smoke Exposure by Plasma Cotinine Levels in Infants and Children Attending Urban Public Hospital Clinics” published in the September 2012 issue of Arch Pediatr Adolesc Med (2012;166[9]:851-856. doi:10.1001/archpediatrics.2012.170, incorrect information appeared. In the last sentence of the Results section of the Abstract, “(geometric mean difference, 6.07 ng/mL [95% CI, 4.37 to 8.43 ng/mL]) ” should be replaced with “(multiplicative factor change in cotinine, 6.01 ng/mL [95% CI, 4.49-8.05 ng/mL]).” This article was corrected online.