Background: Bleomycin, etoposide, cisplatin (BEP) given 3-weekly x 4 remains standard 1st line chemotherapy for metastatic GCTs. Acceleration of standard regimen with shorter cycle lengths has improved cure rates in other cancers. This is the first international randomised clinical trial for intermediate and poor-risk metastatic extracranial GCTs involving both adult and paediatric age group males and females. We aim to determine if accelerated BEP is superior to standard BEP. Methods: DESIGN: Open label, randomised, stratified multicentre, 2 stage, phase 3 trial. Primary endpoint for stage I (n = 150) is complete response rate (RR), and for entire trial (n = 500) is progression free survival (PFS). SAMPLE SIZE: 150 and 500 patients gives > 80% power to detect a 20% improvement in RR and 7% absolute improvement in 2yr PFS, respectively. POPULATION: Males and females aged 11-45 years with intermediate or poor-risk metastatic GCTs of the testis, ovary, retroperitoneum or mediastinum for 1st line chemotherapy. TREATMENT: Randomisation 1:1 to 4 cycles of “standard BEP” or “accelerated BEP”: cisplatin 20mg/m2 IV days (D) 1-5; etoposide 100mg/m2 IV D1-5; bleomycin 30000 IU IV (D 1, 8, 15 or D 2, 9, 16 of a 21 day cycle; D 1, 8 or D 2, 9 of a 14 day cycle); and peg G-CSF or Filgrastim; given every 3 weeks or every 2 weeks respectively. Accelerated BEP arm receives 4 additional weekly doses of bleomycin. ASSESSMENTS: Response assessments at 30 day safety assessment, and 6 months from randomisation or after all post-chemotherapy intervention is completed. Regular follow-up up to 5 years, then annually. Archival tumour tissue and baseline blood collected for translational substudies. STATUS: 25 sites open in ANZ, 1/19 sites open in UK (led by Cambridge Clinical Trials Unit), 41 patients recruited by September 2017. International collaborations with USA (led by Children’s Oncology Group) and Ireland (led by Cancer Trials Ireland) confirmed with sites expected to open by late 2017 and more sites sought for stage 2. Clinical trial information: NCT02582697.