Introduction Prolonged use of antibiotics is closely related to antibiotic-Associated infections, antimicrobial resistance and adverse drug events. The optimal duration of antibiotic treatment for Gram-negative bacteremia (GNB) with a urinary tract source of infection is poorly defined. Methods and analysis Investigator-initiated multicentre, non-blinded, non-inferiority randomised controlled trial with two parallel treatment arms. One arm will receive shortened antibiotic treatment of 5 days and the other arm will receive antibiotic treatment of 7 days or longer. Randomisation will occur in equal proportion (1:1) no later than day 5 of effective antibiotic treatment as determined by antibiogram. Immunosuppressed patients and those with GNB due to non-fermenting bacilli (Acinetobacter spp, Pseudomonas spp), Brucella spp, Fusobacterium spp or polymicrobial growth are ineligible. The primary endpoint is 90-day survival without clinical or microbiological failure to treatment. Secondary endpoints include all-cause mortality, total duration of antibiotic treatment, hospital readmission and Clostridioides difficile infection. Interim safety analysis will be performed after the recruitment of every 100 patients. Given an event rate of 12%, a non-inferiority margin of 10%, and 90% power, the required sample size to determine non-inferiority is 380 patients. Analyses will be performed on both intention-To-Treat and per-protocol populations. Ethics and dissemination The study is approved by the Danish Regional Committee on Health Research (H-19085920) and the Danish Medicines Agency (2019-003282-17). The results of the main trial and each of the secondary endpoints will be submitted for publication in a peer-reviewed journal. Trial registration number ClinicalTrials.Gov:NCT04291768.