The 17th annual study on teen drug abuse, released Thursday, found that more teens had abused a prescription painkiller in 2004 than Ecstasy, cocaine, crack or LSD. One in 11 teens had abused over-the-counter products such as cough medicine, the study reported.

''For the first time, our national study finds that today's teens are more likely to have abused a prescription painkiller to get high than they are to have experimented with a variety of illegal drugs,'' said Partnership Chairman Roy Bostock. ''In other words, Generation Rx has arrived.''

According to the study, the most popular prescription drug abused by teens was Vicodin, with 18 percent - or about 4.3 million youths - reporting they had used it to get high. OxyContin and drugs for attention-deficit disorder such as Ritalin and Adderall followed with one in 10 teens reporting they had tried them.

Fewer than half the teens - 48 percent - said they saw ''great risk'' in experimenting with prescription medicines. ''Ease of access'' was cited as a major factor in trying the medications, with medicine cabinets at home or at friends' homes a likely source, the survey found.

It was only the second year that the survey had studied abuse of legal drugs.

In 2003, the Partnership grouped together three prescription pain relievers: Vicodin, OxyContin and Tylox, and found that 20 percent of teens had tried them.

The 2004 study looked at Vicodin and OxyContin separately but excluded Tylox, and found that 18 percent had tried Vicodin and 10 percent had used OxyContin. The 2004 figures indicated the same or a slight increase in use compared with 2003, said Barbara Delaney, director of research at the Partnership.

For the first time, the 2004 survey included a question about the use of over-the-counter products to get high. Nine percent, or about 2.2 million teens, had experimented with cough syrup and other such products, the survey reported.

It also found that the number of teens reporting marijuana use declined to 37 percent last year, compared with 42 percent a half-dozen years earlier. Over the same amount of time, Ecstasy use declined from 12 percent to 9 percent, while methamphetamine use dropped from 12 percent to 8 percent.