The prevalent use of cannabis by adolescents and young adults, combined with the common misconception that smoking cannabis is relatively harmless, warrants the exploration of factors influencing resistance to health education messages about cannabis use. This investigation did so within a Reversal Theory framework. One hundred and thirteen undergraduate students responded to an informative leaflet detailing the health effects of smoking cannabis. The most significant independent predictor of message resistance was frequency of cannabis use, followed by proactive rebelliousness, autic mastery, health value and ethnicity. These findings have implications for the development, design and targeting of cannabis health education programmes.