Objectives/HypothesisTo determine the effect of otolaryngology trainee participation on clinical outcomes in patients who undergo endoscopic sinus surgery (ESS) for chronic rhinosinusitis. Study DesignSecondary analysis of prospectively collected data. MethodsPatients enrolled in a sinus surgery outcomes study between May 2011 and March 2013 were stratified into two groupsthose who were operated on by an attending alone and those operated on by an attending with a trainee present (resident, fellow, or both). Patients completed quality of life (QOL) surveys including the Chronic Sinusitis Survey (CSS), 22-item Sino-Nasal Outcome Test (SNOT-22), and EuroQol 5-dimension survey preoperatively and 1 year postoperatively. Operative time, estimated blood loss (EBL), complication rates, and survey scores were compared between groups. ResultsThe study population consisted of 452 patients. The attending alone (n=119) and trainee (n=333) groups were statistically comparable in terms of patient demographics, disease severity, and extent of surgery. Mean operative time was significantly shorter in the attending-alone group (80.0 vs. 90.6 minutes, P<.01). Mean EBL (105 mL attending vs. 117 mL trainee, P=.39) and complication rates (3.3% attending vs. 0.6% trainee, P=.07) were similar between groups. Observed changes in QOL measures following ESS were comparable between groups, although absolute improvement in the SNOT-22 scores (19.0 attending vs. 24.5 trainee, P=.05) did show a trend toward greater improvement in the trainee group. ConclusionsTrainee participation in ESS is associated with prolongation in surgical time; however, such participation was not found to adversely affect patient safety or clinical outcomes. Level of Evidence2b Laryngoscope, 126:316-321, 2016