AIM: To investigate the association between environmental factors (perceived availability of marijuana, perceived use among friends and siblings, use of alcohol and tobacco, family structure, parental control, school performance) and lifetime prevalence and frequent and early marijuana use in high school students. ----- METHODS: We used self-reported data from 15-16 years old participants of the 2003 European School Survey Project on Alcohol and Other Drugs (ESPAD) conducted in 11 countries: Denmark, Estonia, Norway, Croatia, Slovenia, Germany, Switzerland, Bulgaria, Czech Republic, Russian Federation, and Ukraine. Multivariate logistic regression was used for data analysis. ----- RESULTS: Countries varied according to lifetime prevalence (8.7%-47.8%) and frequent (8.7%-23.9%) and early (3.0%-13.0%) marijuana use. Daily tobacco smoking was most strongly associated with lifetime marijuana use for boys in 7 and for girls in 5 countries, with highest odds ratio (OR, 95% and confidence interval - CI) for boys in Denmark (OR, 13.52; 95% CI, 8.16-22.4), and for girls in the Czech Republic (OR, 21.21; 95% CI, 12.99-34.62). Perceived marijuana availability was most strongly associated with frequent marijuana use for boys in 4 countries (highest in Slovenia: OR, 19.28; 95% CI, 6.52-57.02) and girls in 5 (highest in Slovenia: OR, 19.05; 95% CI, 5.18-70.04). Perceived use of marijuana among friends was most strongly associated with frequent marijuana use in 5 countries, both for boys (highest in Norway: OR, 23.91; 95% CI, 4.16-137.48) and girls (highest in Denmark: OR, 75.42; 95% CI, 13.11-433.90). Perceived use of marijuana among friends was most strongly associated with early marijuana use in 8 countries for boys (highest in Norway: OR, 54.03; 95% CI, 3.34-875.19) and 3 countries for girls (highest in Denmark: OR, 7.29; 95%CI, 1.77-30.12). ----- CONCLUSION: In each country, marijuana use was associated with similar factors, regardless of marijuana use prevalence in that country.The influence of peer group and perceived availability of marijuana seemed more important than parental control and family structure.