The Standard versus Accelerated Initiation of Renal Replacement Therapy in Acute Kidney Injury (STARRT-AKI) trial is a multinational randomised controlled trial that will enrol a minimum of 2866 patients comparing two strategies for initiating renal replacement therapy in critically ill patients with acute kidney injury.To describe a pre-specified statistical analysis plan (SAP) for the STARRT-AKI trial before completion of patient recruitment and data collection.The SAP was designed by the principal investigators and statisticians and approved by the international STARRT-AKI Steering Committee. The primary and secondary outcomes are defined, the approach to safety monitoring and data collection are summarised, and a detailed description of the planned statistical analyses, including pre-specified subgroup and secondary analyses, is described.We have developed the SAP for the STARRT-AKI trial, including a mock CONSORT diagram, figures and tables. The primary outcome is 90-day all-cause mortality. The primary analysis will be reported as a relative risk (95% CI), absolute risk difference (95% CI), and tested with the χ test. Secondary analyses of the primary outcome will include adjustment for baseline covariates and site, and evaluation for heterogeneity in treatment effect. Pre-specified subgroups will include patient sex, baseline kidney function, illness acuity, surgical status, presence of sepsis, and geographic location.To align with best practice standards for rigour, internal validity and transparency, we have developed a SAP for the STARRT-AKI trial before trial completion. The analysis will adhere to the SAP to avoid bias arising from knowledge of trial results.ClinicalTrials.gov identifier: NCT02568722 (6 October 2015).