Introduction: To investigate the effect of single-dose intravenous antibiotics before emergency department (ED) discharge on the outcomes of patients with urinary tract infections (UTIs). Methods: This is a retrospective study conducted at the EDs of three medical centers. Patients aged over 18 years who presented to the ED with UTI and were discharged without admission between January 1, 2016 and December 31, 2017 were evaluated. The study group received a single dose of effective intravenous antibiotics on the basis of urine culture during the index ED visit following oral antibiotics, while the comparison group received oral antibiotics only. The primary outcomes were ED revisit within 72 h and admission following the return visit.Results: A total of 8168 patients were included. Of these, 20.9% received intravenous antibiotics before ED discharge. Patients who received effective intravenous antibiotics before ED discharge were associated with less than 72-h ED revisit (adjusted odds ratio [OR] 0.791, 95% confidence interval [CI] 0.640-0.979]), but not decreased admission following the return visit (adjusted OR 0.921, 95% CI [0.731-1.153]). In subgroup analysis, parenteral antibiotic use during the index ED visit was associated with decreased admission following ED revisit in patients who presented with fever (adjusted OR 0.605; 95% CI 0.443-0.932). Conclusion: For patients with UTI and clinically well to be discharged from the ED, a single dose of effective intravenous antibiotics before ED discharge was associated with decreased 72-h ED revisit. In patients with febrile UTI, initial intravenous antibiotics were associated with decreased revisit leading to admissions.