Introduction and hypothesisAntibiotic prophylaxis is commonly used when implanting a mid-urethral sling (MUS) for female stress urinary incontinence. Use of antibiotics may lead to adverse events and the development of antibiotic resistance. This study compared a variety of outcomes after MUS surgery with and without antibiotic prophylaxis using data from the national Norwegian Female Incontinence Registry.MethodsPreoperative and 6–12 months postoperative subjective and objective data from 28,687 patients who received MUS surgery from 1998 through 2017 were extracted from the registry. Categorical outcomes were compared between women with or without antibiotic prophylaxis using chi-square test for independence. Primary outcome was incidence of postoperative surgical site infection (SSI). Secondary outcomes were incidence of tape exposure, de novo or persistent urgency urinary incontinence, postoperative pain > 3 months, subjective and objective cure rates, and patient satisfaction.ResultsAntibiotic prophylaxis was used in 9131 and not used in 19,556 patients. SSIs and prolonged postoperative pain occurred significantly more often without antibiotic prophylaxis. Subjective and objective cure rates were significantly higher and tape exposures significantly lower in women not receiving prophylactic antibiotics. There were no significant differences in other outcomes.ConclusionsAntibiotic prophylaxis resulted in fewer women developing postoperative infections or prolonged postoperative pain after MUS surgery, but did not offer protection against tape exposure. The differences in cure rates were small and probably without clinical relevance. If a small increase in surgical site infections is accepted, the routine use of antibiotic prophylaxis can probably be omitted.