INTRODUCTION: A reduction in smoking among adolescents has been a key issue in health promotion for many years and there have been many initiatives to reduce smoking initiation. The objective was to describe the proportion of smokers and daily smokers among 11-, 13-, and 15-year-old girls and boys from 1988 to 2006. MATERIALS AND METHODS: We used data from six comparable cross-sectional studies from 1988, 1991, 1994, 1998, 2002 and 2006. Each study comprised 11-, 13-, and 15-year-old students from a random sample of schools, total n = 23,871. Smoking was measured by self-reports and the paper presents percent of daily smokers and percent of smokers. RESULTS: The proportion of smokers was 14-18% in the 1980s and 1990s. It declined to 12.8% in 2002 and 10.3% in 2006 (test for trend, p < 0.0001). The proportion of daily smokers was 6-8% in the 1980s and 1990s. It declined to 5.4% in 2002 and 3.8% in 2006 (p < 0.0001). There were only a few smokers among the 11-year-olds and no changes appeared in the period 1988-2006. There was a significant decline in the proportion of smokers among 13-year-old girls but not among boys. There was a significant decline in the proportion of smokers and daily smokers among 15-year-old girls but not among boys. Analyses restricted to the three latter studies from 1998, 2002, and 2006 show a significant decline in the proportion of smokers and daily smokers among both 15-year-old girls and boys. CONCLUSION: The proportion of smokers and daily smokers among 11-15-year-olds declined during the period 1988-2006, most pronounced among 13- and 15-year-old girls.