Background: This study examined trends in the prevalence of smoking and snuff use among Norwegian adolescents in lower secondary school (ages 13–15 years) from a national survey conducted every 5 years between 1975 and 1995. Methods: Pupils completed a brief written questionnaire on tobacco use and related information. Local school administrators coordinated data collection and forwarded a sample of completed questionnaires to the National Council on Tobacco and Health for compilation and analysis. Effects for age, gender and survey year were examined using logistic regression analysis. Overall, 24,127 pupils in five different cohorts were included. Results: Smoking was highest in 1975 when 45.5% of youth reported smoking either daily or occasionally (figures adjusted for age and gender). Smoking declined each year thereafter through to 1990 (23.6%) but increased in 1995 (26.0%), primarily due to an increase in occasional smoking. Like smoking, snuff use declined between 1985 and 1990 but Increased in 1995. All changes across survey years were statistically significant. Smoking was higher among girls than boys, while snuff use was much higher among boys. Conclusion: Several hypotheses that might account for the recent increase were examined with the most likely factor being Norway’s low allocation of resources for educational interventions and public information campaigns during the years studied. However, in the past 2 years Norway has undertaken a number of new tobacco control initiatives that may result in reversal of the most recent trends.