The study was authorized by Congress in 1997.
Researchers tracked four groups of children in two rural and two urban communities, half of them given abstinence-only training. All the children received whatever sexual education was routinely given in their community.
When the study ended, the children's average age was just under 17. By that time, almost half had become sexually active, The Washington Post reported.
Fewer than 25 percent of the sexually active group reported consistent condom, use while 1/3 had had multiple partners. Teens who had been through abstinence-only education had the same behavior as the others.
Harry Wilson, an official with the Department of Health and Human Services, criticized the study, saying it was not rigorous enough. He said the administration's funding of abstinence-only programs will remain unchanged.
Others praised the study.
"There's not a lot of good news here for people who pin their hopes on abstinence-only education," said Sarah Brown, executive director of the National Campaign to Prevent Teen Pregnancy.