AbstractObjectivesPostoperative infection is the most common complication after septoplasty. Pre‐ or postoperative prophylactic antibiotics are commonly used, although no official guidelines exist.DesignWe retrospectively collected data on postoperative infections from 772 septoplasties performed in 2015, 2016 and 2018, and classified the infections according to surgical site infection (SSI) criteria by the Centers for Disease Control and Prevention (CDC). We evaluated the infections according to antibiotic use (preoperative or postoperative, both, or none) and accounted for patient and surgical confounding factors. We compared the results with three previous studies from our department to find out the trend in the occurrence of postoperative infections and in the use of antibiotics.ResultsTwenty‐nine cases (3.8%) fulfilled CDC infection criteria. Any kind of antibiotic prophylaxis reduced the risk of SSI (p = .018). One dose of intravenous cefuroxime before incision was the most effective preventive measure (p = .045). We found no significant effect of postoperative antibiotics. However, postoperative antibiotics lowered the infection rate to 1.8% compared to 6.1% among those not treated with any antibiotics. The only other factor reducing the risk of SSI was local anaesthesia compared with general anaesthesia.ConclusionPreoperative antibiotic prophylaxis effectively reduced postoperative infection rate after septoplasty.