Problem: Third molar removal in sagittal split osteotomies(SSOs) is recommended by some authors at least 6 months preoperatively to prevent unfavorable fractures. Others authors suggest concomitant removal. The purpose of this study was to investigate the effect of third molars during SSOs. Methods: A prospective study of 677 SSOs was conducted. GroupI consisted of 331 SSOs and third molar removal. GroupII consisted of 346 SSOs without third molar. Intraoperative and postoperative evaluations were recorded. Results: The overall rate of unfavorable fractures was 3.1%, with incidences of 2.4% in GroupI, compared to 3.8% in GroupII(P=0.3). The rate of IAN entrapment was lower in GroupI(37.2%) than in GroupII(46.5%;P=0.01). Third molars increased procedural time by 1.7 minutes. Neurosensory deficits were higher in GroupII. Conclusion: Removal of third molars during SSOs is not associated with increased incidence of unfavorable fractures. Their presence decreases IAN entrapment, improve neurosensory recovery, but slightly increases operating time.