The survey, conducted for 33 years, found that nearly 10 percent of high school seniors reported nonmedical use of Vicodin and 4.7 percent reported abusing OxyContin. Both are strong opioid pain pills. Seven of the top 10 drugs abused by high school seniors were prescription or over-the-counter medications.

Abuse of prescription drugs continues to be a major problem among teenagers, although fewer are smoking cigarettes, the 2008 Monitoring the Future survey reported last week.

The survey, conducted for 33 years, found that nearly 10 percent of high school seniors reported nonmedical use of Vicodin and 4.7 percent reported abusing OxyContin. Both are strong opioid pain pills. Seven of the top 10 drugs abused by high school seniors were prescription or over-the-counter medications.

"While the long-term general decline (in drug abuse) is encouraging, especially for cigarettes and alcohol, some of the other findings this year amplify our concerns for potential problems in the future — especially the nonmedical use of prescription drugs," said Dr. Nora D. Volkow, director of the National Institute on Drug Abuse, which funds the study, in a statement. Monitoring the Future is conducted by researchers at the University of Michigan.

The survey found that marijuana use has leveled off after a decade-long decline. Cigarette smoking is at its lowest point since the survey began — though more than 1 in 10 high school seniors say they smoke daily and 5.4 percent smoke more than a half a pack a day.