Funding: We acknowledge support from Cancer Research UK C5047/A14835/A22530/ A17528, C309/A11566, C368/A6743, A368/A7990, C14303/A17197 (Z.K.-J., S. Merson, N.C., S.E., D.L., T. Dadaev, M.A., E.B., J.B., G.A., P.W., B.A.-L., D.S.B., C.S.C., R.A.E.), the Dallaglio Foundation (CR-UK Prostate Cancer ICGC Project and Pan Prostate Cancer Group), PC-UK/Movember (Z.K.-J.), the NIHR support to The Biomedical Research Centre at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust (Z.K.-J., N.D., S. Merson, N.C., S.E., D.L., T. Dadaev, S. Thomas, M.A., E.B., C.F., N.L., D.N., V.K., N.A., P.K., C.O., D.C., A.T., E.M., E.R., T. Dudderidge, S. Hazell, J.B., G.A., P.W., B.A.-L., D.S.B., C.S.C., R.A.E.), Cancer Research UK funding to The Institute of Cancer Research and the Royal Marsden NHS Foundation Trust CRUK Centre, the National Cancer Research Institute (National Institute of Health Research (NIHR) Collaborative Study: “Prostate Cancer: Mechanisms of Progression and Treatment (PROMPT)” (grant G0500966/75466) (D.E.N., V.G.), the Li Ka Shing Foundation (D.C.W., D.J.W.), Canadian Institutes of Health Research (CIHR) Project Grant (J.R.), and the Academy of Finland and Cancer Society of Finland (G.S.B.). D.M.B. is supported by Orchid. C.V.’s academic time was supported by the NIHR Oxford Biomedical Research Centre (Molecular Diagnostics Theme/Multimodal Pathology sub-theme). We also acknowledge support from the Bob Champion Cancer Trust, The Masonic Charitable Foundation successor to The Grand Charity, The King Family and the Stephen Hargrave Trust (C.S.C., D.S.B.). P.W. is a Cancer Research Life Fellow. We acknowledge core facilities provided by CRUK funding to the CRUK ICR Centre, the CRUK Cancer Therapeutics Unit and support for canSAR C35696/A23187 (P.W., G.A.). We would like to acknowledge The D. J Fielding Medical Research Trust for its support. Background: Germline variants explain more than a third of prostate cancer (PrCa) risk, but very few associations have been identified between heritable factors and clinical progression. Objective: To find rare germline variants that predict time to biochemical recurrence (BCR) after radical treatment in men with PrCa and understand the genetic factors associated with such progression. Design, setting, and participants: Whole-genome sequencing data from blood DNA were analysed for 850 PrCa patients with radical treatment from the Pan Prostate Cancer Group (PPCG) consortium from the UK, Canada, Germany, Australia, and France. Findings were validated using 383 patients from The Cancer Genome Atlas (TCGA) dataset. Outcome measurements and statistical analysis: A total of 15,822 rare (MAF