INTRODUCTION Orthognathic surgery, being an invasive surgical procedure, can present important postoperative morbidities for the patient. Surgical site infection is one of the most frequently described complications. In view of this, the administration of prophylactic antibiotics prior to this type of procedure appears to be a frequent practice. However, the cost-benefit of the use of antibiotics, the type of antibiotic, the route of administration, the dosage, and the scheme to be used have not been clearly defined and are presented as controversial issues. In this summary of evidence, the usefulness of the long-term versus the short-term prophylactic scheme will be compared. METHODS We conducted a search in Epistemonikos, the largest database of systematic reviews in health, which is maintained by screening multiple sources of information, including MEDLINE, EMBASE, Cochrane, among others. We extracted data from the identified reviews, analyzed data from the primary studies, performed a meta-analysis, and prepared a summary table of results using the GRADE method. RESULTS AND CONCLUSIONS We identified five systematic reviews that together included nine primary studies, all of which correspond to randomized trials. We conclude that giving a long-term antibiotic prophylactic regimen probably decreases the risk of surgical site infection and could increase the risk of hospital stay longer than two days, but on this last point, the certainty of the evidence is low.