Young children are vulnerable to inadvertent exposure to prescription and over-the-counter (OTC) medications, especially when these items are not stored securely. In 2002, according to death certificate data, 35 children aged < or =4 years died from unintentional medication poisonings in the United States (CDC, unpublished data, 2005). In 2003, according to reports to U.S. poison control centers, pharmaceuticals accounted for 1,336,209 (55.8%) of unintentional chemical or substance exposures. Of those pharmaceutical exposures, 568,939 (42.6%) involved children aged <6 years. For this report, CDC analyzed 2001-2003 data from hospital emergency department (ED) visits reported by the National Electronic Injury Surveillance System--All Injury Program (NEISS-AIP). The results of this analysis indicated that, during 2001-2003, an estimated 53,517 children aged < or =4 years were treated annually in U.S. EDs for unintentional medication exposures. An estimated 72% of these exposures were in children aged 1-2 years. Children aged < or =4 years can reach items on a table, in a purse, or in a drawer, where medications are often stored; young children also tend to put objects they find in their mouths. Parents and others responsible for supervising children should store medications securely at all times, keep them out of the reach of children, and be vigilant in preventing access by children to daily-use containers such as pill boxes.