INTRODUCTION: E-cigarettes (ECs) may benefit smokers with mental health conditions who are more likely to smoke, and smoke more heavily, than those without mental health conditions. This could be undermined if harm misperceptions in this group are high as is the case in the general population. This study aimed to assess EC harm perceptions relative to cigarettes as a function of mental health status and a variety of characteristics. METHODS: Data were collected from 6,531 current smokers in 2016/17 in household surveys of representative samples of adults. The associations of mental health status (self-reported mental health condition and past year treatment), smoking and EC use characteristics, and characteristics relating to use of potential information sources with harm perceptions of ECs relative to cigarettes (measured by correct response 'less harmful' vs wrong responses 'more harmful', 'equally harmful', 'don't know') were analysed with logistic regression. RESULTS: A similar proportion of smokers without mental health conditions (61.5%, 95% CI 60.1-62.9) and with mental health conditions (both with [61.3%, 95% CI 58.7-63.8] and without past year treatment [61.5%, 95% CI 58.1-64.7] held inaccurate EC harm perceptions (all P>0.05). Being female, non-white, aged 25-34 compared with 16-24, from lower social grades (C2, D and E), not having post-16 qualifications, no EC experience, a daily smoker, unmotivated to quit <1 month, non-internet user and non-broadsheet reader were all associated with more inaccurate harm perceptions (all P<0.05). CONCLUSIONS: The majority of smokers in England have inaccurate harm perceptions of ECs regardless of mental health status
