BACKGROUND: Research fraud is often seen as a rare event, but evidence from self-report surveys indicates that fabrication and falsification of data are common enough to be a problem. This study assessed attitudes to serious research misconduct, contrasting views of self-appointed research "sleuths" and research integrity (RI) experts. METHODS: Respondents completed a two-round Delphi survey, rating agreement with statements about prevalence, responses to, and consequences of serious research misconduct. In Round 1, there were 95 respondents (37 sleuths, 33 RI experts and 25 other). For Round 2, there were 79 respondents (36 sleuths, 22 RI experts and 21 other). RESULTS: Respondents agreed on the damaging impact of academic incentive structures on research integrity, and the importance of agencies working together to address serious research misconduct and preserve the academic record. There was polarization of views between sleuths and RI experts on the frequency of serious research misconduct, the adequacy of institutional responses, and the suitability of self-regulation by institutions. CONCLUSION: Sleuths and RI experts operate in information silos. They could benefit from working together, but this will only be possible if trust is restored. Institutional self-regulation has drawbacks. Strengths and weaknesses of alternative regulatory models need to be evaluated.