BackgroundSepsis is a major challenge in critical care and is associated with high mortality. Current management of sepsis and septic shock remains mainly supportive. Both basic and clinical research has shown that ulinastatin can improve the prognosis of sepsis. The aim of this trial is to evaluate the efficacy and safety profiles of ulinastatin compared with placebo.Methods/designIn this multi-center, double-blind, randomized placebo-controlled trial we are recruiting a total of 348 subjects meeting “The Third International Consensus Definitions for Sepsis and Septic Shock” (Sepsis-3). Subjects will be randomized (1:1) to receive ulinastatin 400,000 IU three times a day for 10 days or matching placebo and usual care simultaneously. The primary outcome is 28-day all-cause mortality. Adverse events and serious adverse events will be monitored closely.DiscussionADJUST is a large, multi-center, double-blind, randomized, parallel-group, placebo-controlled trial of ulinastatin in mainland China and is well-designed on the basis of previous studies. The results of this trial may help to provide evidence-based recommendations for treatment of sepsis.Trial registrationClinicalTrials.gov, ID: NCT02647554. First registered on 27 December 2015, and last verified in December of 2016.Protocol version: 2.1, verified on 19 July 2016.