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 improves overall survival (OS) in castration-resistant, metastatic prostate cancer. We hypothesized that the addition of enzalutamide to adjuvant ADT and RT will improve outcomes. The aim is to determine the effects of enzalutamide versus a conventional non-steroidal anti-androgen (NSAA) as part of neoadjuvant and adjuvant ADT in men undergoing RT for high risk, localized PC. Methods: DESIGN: Open label, randomised, phase 3 trial including ANZ, USA, UK, Ireland and Europe. ENDPOINTS: OS (primary), cause-specific survival, PSA progression free survival (PFS), clinical PFS, time to subsequent hormonal therapy, time to castration-resistant disease (PCWG2 criteria), metastasis free survival (MFS), adverse events and health-related quality of life (HRQOL). CORRELATIVE OBJECTIVES: identification of prognostic/predictive biomarkers from archival tumour tissue and serial blood samples. SAMPLE SIZE: 800 participants with a minimum follow-up of 5.5 yrs is designed to give 80% power to detect 33% reduction in the hazard of death assuming 5-year survival rate of 76% amongst controls. TREATMENT: Enzalutamide 160mg daily for 24 months versus conventional NSAA for 6 months. All participants receive LHRHA for 24 months, and RT starting about week 16 delivered as 78Gy in 39#, or 46Gy in 23# 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. Imaging with CT/MRI and bone scan at baseline, PSA progression, then 6 monthly until re-initiation of ADT, when PCWG2 criteria for CRPC are met and then 3 monthly until evidence of metastases. 623 participants recruited from 61 sites as of 16 October 2017. ENZARAD is an investigator-initiated cooperative group trial led by ANZUP Cancer Trials Group with funds and product from Astellas. Clinical trial information: NCT02446444