The use of antibiotics is a common practice among otorhinolaryngogists for surgical procedures. The majority of the American Rhinology Society members uses postoperative antibiotics routinely in septoplasties, which is considered unnecessary by many authors. Aim: To study the real necessity of the antibiotic usage in septoplasties, as well as the main post-operative complications described in the literature. Study design: clinical prospective with transversal cohort. Material and Method: We studied prospectively 35 patients who were undergone to septoplasty with or without turbinectomy, in the Clinical Hospital of the University of São Paulo. The patients were splited in three groups: Group A: without antibiotics; Group B: antibiotics (cefazolin) only during the anesthesical induction; Group C: antibiotics both in the anesthesical induction and post-operatively for seven days. A questionnaire was applied in the immediate postoperatory, in the 7th post-operative day and in the 30th post-operative day asking for bleeding, fever, pain, nauseas, vomits and followed by physical and endoscopic evaluation looking for hematoma, septal abscess and purulent secretion which as quantified. Result: We do not observed significative difference among the groups concerning to pain, fever, nauseas, vomits, bleeding and purulent secretion. None of the patients had hematoma or septal abscess. The groups also do not differ in respect to the quantity of purulent secretion. Conclusion: The nasal surgeries are clean contamined and do not need antibioticprophilaxy because of the low infection risk.