problematic substance use is one of the top disparities affecting indigenous people. among non-indigenous people, specific personality traits and drinking motives are associated with problematic patterns of alcohol use. the modified drinking motives questionnaire – revised (mdmq-r) is a measure for examining drinking motives among youth and adults. despite cross-cultural use, the mdmq-r demonstrated a different factor structure among indigenous youth in canada (mushquash et al., 2014). the mdmq-r has also been examined in relation to personality traits, where findings suggest that specific personality traits and drinking motives together are associated with problematic patterns of alcohol use. this study examined the factor structure of the mdmq-r in a substance use treatment-seeking sample of indigenous adults. additionally, this study sought to understand how personality traits are related to substance use motives. sex differences regarding substance use motives were investigated as well. as hypothesized, a three-factor structure solution received support, consistent with findings among indigenous youth. hypotheses regarding personality traits were supported, whereby positive reinforcement motives were associated with impulsivity and sensation-seeking traits, and negative reinforcement motives were associated with hopelessness and anxiety sensitivity traits. sex was not predictive of higher scores on any mdmq-r subscales. examining the mdmq-r structure may provide culturally relevant information about the use of this measure with indigenous populations in canada. these findings may inform future research led by indigenous communities to understand better the needs of their members facing problematic substance use.