Introduction & Objectives: Deferred active treatment (DAT)strategies for men with low risk localised prostate cancer are an alternative to radical intervention and aims to avoid overtreatment consequences. DAT remains controversial, with uncertainty and heterogeneity in many aspects of patient eligibility, follow up, reclassification, triggering active treatment and outcomes. This uncertainty inhibits optimal practice. Due to lack of high-level evidence we aimed to achieve consensus to guide clinical practice and research. Materials & Methods: A project steering group was convened comprising of clinical and methods experts from the EAU's prostate cancer guidelines panel and methods committee. Project[i]and review[ii]protocols were published. We initiated a 3 phase consensus project: 1)A systematic review to describe and categorise heterogeneity in DAT studies; 2)We used the findings of the review to inform statements which we sought consensus on in a 2-round Delphi involving healthcare professionals (HCPs)purposively sampled from a variety of international professional societies and patients purposively sampled form various European prostate cancer advocacy groups. HCPs scored 134 statements and patients scored 10. Scoring was on a Likert scale of 1 (strongly disagree)to 9 (strongly agree)or ‘unable to score’; and 3)A 1-day face-to-face consensus meeting sampled from Delphi-completers with structured discussion and voting on unclear statements from the Delphi, involving HCPs and patients. Results: The results are summarised in Figure 1. [Figure Presented]A large international panel of clinical experts and patients were included and consensus was reached on 75% of the statements. Conclusions: We sought opinion from HCP experts on all the parameters of DAT, and the expertise from patients on the most important outcomes. We reached consensus on the majority of statements. This information will be used to inform clinical practice guidelines until higher levels of evidence emerge. [i]Lam, T.B.L et al Study Protocol for the DETECTIVE Study: An International Collaborative Study To Develop Consensus Statements for Deferred Treatment with Curative Intent for Localised Prostate Cancer. Euro. Urol. 2018 (in press)[ii]Willemse P-P et al. Systematic review of deferred treatment with curative intent for localised prostate cancer to explore heterogeneity of definitions, thresholds and criteria and clinical effectiveness.