Purpose: To determine whether performing an inferior meatal antrostomy as a prophylactic intraoperative maneuver in patients who underwent zygomatic implant surgery significantly reduces the incidence of postoperative sinusitis. Materials and Methods: A double-blind randomized controlled trial was implemented. The study included 44 patients seen at the Oral and Maxillofacial Surgery Department at Universidad El Bosque in Bogota, Colombia, who required zygomatic implant surgery. Patients were randomly allocated to either group 1 (without inferior meatal antrostomy) or group 2 (with inferior meatal antrostomy). Patients were evaluated clinically and radiographically 15 days and 3 months after surgery, and classified depending on whether they did or did not develop sinusitis. Results were analyzed using descriptive and bivariate statistics. The control group event rate, experimental group event rate, relative risk, relative risk reduction, absolute risk reduction, and number needed to treat values were calculated for further analysis. Results: Three patients allocated to group 1 showed clinical and radiographic signs of sinusitis after zygomatic implant surgery, for an overall rate of sinusitis of 13.6%. No patient in group 2 developed clinical or radiographic signs of sinusitis. Conclusion: The results of this study suggest that performing an inferior meatal antrostomy as a prophylactic intraoperative maneuver in patients who require zygomatic implant surgery is an effective method to prevent postoperative sinusitis. Keywords: inferior meatal antrostomy, sinusitis, zygomatic implants