One of the 10 Leading Health Indicators that reflect the major health concerns in the United States is cigarette smoking among adolescents. To examine changes in cigarette smoking among high school students in the United States from 1991 to 1999, CDC analyzed data from the national Youth Risk Behavior Survey (YRBS). This report summarizes the results of the analysis and indicates that current smoking among U.S. high school students increased significantly from 27.5% in 1991 to 34.8% in 1999; however, the analysis also suggested that, later in the decade, current smoking may have leveled or possibly begun to decline.