One in five 15-year-olds have admitted using drugs - mostly cannabis - on a regular basis, according to figures.
Cannabis was the drug of choice among teenagers
The findings were largely the same as in 2002, despite government anti-drug campaigns.
The figures were disclosed in the Scottish Schools Adolescent Lifestyle and Substance Use Survey.
The survey also found that drugs were now preferred over cigarettes by teenage boys and 15-year-old girls drink more often than young males.
Of the 7,000 teenagers questioned, 20% of teenagers said they had taken drugs in the month before the survey was carried out.
Experts found as many as 7% of 13-year-olds admitted taking drugs.
Cannabis was the drug of choice, rather than tobacco, for 15-year-old boys. Smoking cigarettes was still more popular among girls, of whom 24% admitted smoking.
The study found that 46% of girls and 40% of boys admitted drinking alcohol in the week before they were quizzed by researchers.
However smoking, drinking and taking drugs appeared to be on the decline among 13-year-olds.
The findings followed a study which suggested that alcohol may be a greater problem than drugs for young teenagers.
The research was published in January by Health Scotland.