Accelerated surgery; Acute kidney injury; Hip fracture Cirugía acelerada; Lesión renal aguda; Fractura de cadera Cirurgia accelerada; Lesions renals agudes; Fractura de maluc Introduction: Inflammation, dehydration, hypotension and bleeding may all contribute to the development of acute kidney injury (AKI). Accelerated surgery after a hip fracture can decrease the exposure time to such contributors and may reduce the risk of AKI. Methods and analysis: Hip fracture Accelerated surgical TreaTment And Care tracK (HIP ATTACK) is a multicentre, international, parallel-group randomised controlled trial (RCT). Patients who suffer a hip fracture are randomly allocated to either accelerated medical assessment and surgical repair with a goal of surgery within 6 hours of diagnosis or standard care where a repair typically occurs 24 to 48 hours after diagnosis. The primary outcome of this substudy is the development of AKI within 7 days of randomisation. We anticipate at least 1998 patients will participate in this substudy. Ethics and dissemination: We obtained ethics approval for additional serum creatinine recordings in consecutive patients enrolled at 70 participating centres. All patients provide consent before randomisation. We anticipate reporting substudy results by 2021. Trial registration number: NCT02027896; Pre-results. This work was supported by the following grants: Canadian Institute of Health and Research (CIHR) Foundation Award, CIHR’s Strategy for Patient Oriented Research (SPOR), through the Ontario SPOR Support Unit, which is supported by the CIHR and the Province of Ontario, as well as the Ontario Ministry of Health and Long-Term Care, and a grant from Smith & Nephew to recruit 300 patients in Spain. Grants to support this substudy were provided by the Department of Medicine at Western University. Dr Devereaux was supported by a Tier 1 Canada Research Chair in Perioperative Medicine. Dr Amit Garg was supported by the Dr Adam Linton Chair in Kidney Health Analytics and a CIHR Clinician Investigator Award.