Background: Adjuvant ADT with an LHRH analog (LHRHA) given before, during and after radiotherapy (RT) is standard of care for high risk localised prostate cancer (PC). Enzalutamide is more effective in metastatic disease than conventional non-steroidal anti-androgens (NSAA). We hypothesize that addition of enzalutamide to adjuvant ADT and RT will improve outcomes. The aim is to determine the efficacy of enzalutamide compared with NSAA as part of adjuvant ADT with LHRHA in men planned for RT for localized high risk or node-positive PC. Methods: DESIGN: Open label, randomised, phase 3 trial including ANZ, USA, UK, Ireland and Europe. ENDPOINTS: OS (primary), cause-specific survival, PSA PFS, clinical PFS, time to subsequent hormonal therapy, time to castration-resistant disease (PCWG2 criteria), metastasis free survival, adverse events and HRQOL. Tertiary objectives: identification of prognostic/predictive biomarkers from archival tumour tissue and 4 serial fasting bloods. 800 target participants with 5.5 yrs minimum follow-up. 80% power to detect 33% reduction in the hazard of death assuming 5-year survival rate of 76% amongst controls. TREATMENT: Participants are randomised 1:1 to enzalutamide 160mg daily for 24 months versus conventional NSAA for 6 months. All participants receive LHRHA for 24 months and RT starting after week 16. RT delivered as 78Gy in 39 Fx or 46Gy in 23 Fx plus brachytherapy (nodal RT optional for N0, mandatory for N1). ASSESSMENTS: Baseline, then every 8 weeks until year 2, then 3-4 monthly until year 5, 6-monthly until year 7, then annually. CT/MRI and bone scan at baseline, PSA progression, 6 monthly until re-initiation of ADT, when PCWG2 criteria for CRPC are met and then 3 monthly until evidence of metastases. As of 1^st February 2017, 55 of 67 sites open with 398 patients recruited. EORTC sites expected to open from Quarter 1 2017. ENZARAD is an investigator-initiated cooperative group trial led by ANZUP Cancer Trials Group with funds and product from Astellas. ANZUP is supported by Cancer Australia and previously CI NSW. ClinicalTrials.gov: NCT02446444, ANZCTR: ACTRN12614000126617 Clinical trial information: NCT02446444