Aim. To examine the characteristics of marijuana users among a large sample of American Indian high school students. Design. High school survey. Setting. Seven predominantly American Indian high schools in four communities west of the Mississippi. Participants. 1464 Indian adolescents who: (1) completed a survey in November, 1993, (2) were in grades 9 to 12, (3) were members of one of four Indian tribal groups; and (4) had a complete set of data for these analyses. Measurements. Logistic regression models were developed to predict the probability of low-frequency (1-3 times over the last month) and high-frequency (11 or more times) marijuana use. Independent variables included measures of socio-demographics, stressful life events, personal characteristics and beliefs, psychiatric symptomatology and other substance use. Findings. Forty per cent of these American Indian adolescents had used marijuana at least once in the last month. The prevalence of marijuana use varied across the four tribes. Males were no more likely than females to use marijuana at a low frequency, but were more likely to use at a high frequency. The factors associated with marijuana use varied with the frequency of use and by gender. In the final multivariate models, low-frequency marijuana use among females was associated with reporting that peers encouraged alcohol use as well as use of alcohol and stimulants. Among males, low-frequency use was associated with greater positive alcohol expectancies, lower grades in school and alcohol use. While high-frequency marijuana use was associated with use of alcohol, stimulants and cocaine among females, such use was associated with higher scores on the antisocial behavior scale as well as the use of alcohol, stimulants and cocaine among males. Overall, the strongest associations were with the use of alcohol and other illicit substances. Conclusion. Low-frequency and high-frequency marijuana use are distinct patterns of use and have different correlates across genders. Marijuana use among American Indian adolescents is a complex phenomenon that is best understood within the context of other substance use.