Claudio Stacchi, DDS, MSc/Francesca Andolsek, DDS, MSc/Federico Berton, DDS, MSc/Giuseppe Perinetti, DDS, MSc, PhD/Chiara Ottavia Navarra, DDS, MSc/Roberto Di Lenarda, DDS, MSc: Purpose: To analyze the occurrence of intraoperative complications during sinus floor elevation with a lateral approach and their correlations with the technique adopted by surgeons. Materials and Methods: Electronic and manual searches resulted in 4,417 records on sinus floor elevation. Twenty-one randomized clinical trials (RCTs) and 11 prospective controlled clinical trials (CCTs) reporting occurrence of intraoperative complications were included. Risk of bias was assessed according to the Cochrane tool and a modified Downs and Black quality analysis for RCTs and CCTs, respectively. Results: Sinus membrane perforation and hemorrhagic events following vascular lesions were the only intraoperative complications reported by the selected studies with overall occurrences of 15.7% and 0.4%, respectively. Three different surgical devices (rotary instruments, piezoelectric osteotomes, and manual bone scrapers) were used to perform the lateral antrostomy. Ultrasonic devices and bone scrapers showed a lower incidence (10.9% and 6.0%, respectively) of membrane perforation compared with that of rotary instruments (20.1%). Among the different ultrasonic procedures, erosion of the lateral antral wall showed the lowest membrane perforations (4.7% incidence). Hemorrhagic complications seemed to be extremely infrequent with any surgical technique. Conclusion: Sinus membrane perforation was the most frequently described intraoperative complication during sinus floor elevation with a lateral approach. Thinning the lateral wall of the sinus before performing the antrostomy (either with ultrasonic devices or manual bone scrapers) seemed to be an important factor in preventing membrane perforation during sinus surgery. Further high-quality RCTs specifically investigating intraoperative complication occurrence are needed.