There is reason to believe that health-related misinformation, fake news and conspiracy theories can undermine our efforts to combat the spread of the COVID-19 pandemic. In particular, there is a concern that those who have been exposed to misinformation related to the virus may be less likely to comply with public health measures (e.g. someone who sees a Facebook post about masks increasing the amount of carbon dioxide in the blood may be less willing to actually wear a mask). Though this question is of clear societal importance, much of this discourse is founded on anecdotes rather than data. Furthermore, the explosion of COVID-19 research in the past year has made it difficult to synthesise the evidence in this area. There is thus an urgent need to systematically review research on the behavioural effects of exposure to health misinformation. The proposed project is a systematic review of the effects of COVID-19 misinformation on health-related behaviours, such as social distancing and intentions to get vaccinated. This review will integrate, evaluate and summarise the findings of peer-reviewed studies which have assessed whether exposure to COVID-19 misinformation significantly impacts these behaviours. This review is necessary to determine the extent to which COVID-19 misinformation is a genuine threat to population health during the pandemic and will allow for an estimation of the size of such an effect. This review will therefore be of great use to medics, policy-makers, and members of the public.