Bringing evidence into policy and practice discussions is political; more so when evidence from health studies or programme data are deemed controversial or unexpected, or when results are manipulated and misrepresented. Furthermore, opinion and misinformation in recent years has challenged our notions about how to achieve evidence-informed decision-making (EIDM). Health policy and systems (HPS) researchers and practitioners are battling misrepresentation that only serves to detract from important health issues or, worse, benefit powerful interests. This paper describes cases of politically and socially controversial evidence presented by researchers, practitioners and journalists during the Health Systems Research Symposium 2020. These cases cut across global contexts and range from public debates on vaccination, comprehensive sexual education, and tobacco to more inward debates around performance-based financing and EIDM in refugee policy. The consequences of engaging in controversial research include threats to commercial profit, perceived assaults on moral beliefs, censorship, fear of reprisal, and infodemics. Consequences for public health include research(er) hesitancy, contribution to corruption and leakage, researcher reflexivity, and ethical concerns within the HPS research and EIDM fields. Recommendations for supporting researchers, practitioners and advocates include better training and support structures for responding to controversy, safe spaces for sharing experiences, and modifying incentive structures.