•We examined 3 measures of driving under the influence of cannabis (DUIC).•Adults with chronic pain were seeking medical cannabis certification.•Past 6-month DUIC rates were: 56% within 2 h, 51% a little high, 21% very high.•Prevalence of DUIC was high and interventions should be developed for prevention. Driving under the influence of cannabis (DUIC) is a public health concern among those using medical cannabis. Understanding behaviors contributing to DUIC can inform prevention efforts. We evaluated three past 6-month DUIC behaviors among medical cannabis users with chronic pain. Adults (N = 790) seeking medical cannabis certification or recertification for moderate/severe pain were recruited from February 2014 through June 2015 at Michigan medical cannabis clinics. About half of participants were male (52%) and 81% were White; their Mean age was 45.8 years. Participants completed survey measures of DUIC (driving within 2 h of use, driving while “a little high,” and driving while “very high”) and background factors (demographics, alcohol use, etc.). Unadjusted and adjusted logistic regressions were used to examine correlates of DUIC. For the past 6 months, DUIC within 2 h of use was reported by 56.4% of the sample, DUIC while a “little high” was reported by 50.5%, and “very high” was reported by 21.1%. Greater cannabis quantity consumed and binge drinking were generally associated with DUIC behaviors. Higher pain was associated with lower likelihood of DUIC. Findings vary somewhat across DUIC measures. The prevalence of DUIC is concerning, with more research needed on how to best measure DUIC. Prevention messaging for DUIC may be enhanced by addressing alcohol co-consumption.