Introduction: Bioabsorbable steroid-eluting implants are available as an adjunct for endoscopic sinus surgery (ESS) in the treatment of chronic rhinosinusitis (CRS). It is unclear which patients are most likely to benefit from this technology. We sought to determine if the severity of preoperative sinonasal inflammation influences the postoperative changes in patient-reported quality of life (QOL) and endoscopic appearance following ESS with implant placement; Methods: Consecutive adult patients undergoing ESS for CRS with ethmoidectomy and placement of a steroid-eluting implant over an 18-month period were prospectively included for study. Pre-operative sinus computed tomography (CT) opacification was evaluated using the Lund-Mackay score (LMS). Sinonasal Outcome Test (SNOT-22) scores and Lund-Kennedy endoscopic scores (LKES) for each patient were collected preoperatively and at three- and six-month intervals postoperatively. Serum eosinophilia (>6.0% on peripheral smear) and sinus tissue eosinophilia were recorded; Results: One hundred and thirty-six patients were included for analysis. Of these, 36.7% had polyposis, 15.4% had serum eosinophilia and 64.0% had tissue eosinophilia. The mean (standard deviation) SNOT-22 score was 45.5 (19.4) preoperatively, which improved postoperatively to 18.8 (14.1) at three months (p
< 0.001) and 16.5 (14.0) at six months (p
< 0.001). Similar results were found when stratified by the presence of polyposis, serum eosinophilia, tissue eosinophilia or high-grade CT findings (LMS > 6). Higher baseline LKES was observed for patients with eosinophilia or high-grade LMS, but these differences normalized at six months postoperatively; Conclusions: Patient-reported QOL and endoscopic appearance show improvement six months after placement of a steroid-eluting implant during ESS, irrespective of the presence of polyposis or eosinophilia.