The endoscopic endonasal approach (EEA) has become the preferred treatment for pituitary tumors, with minimal sinonasal morbidity. However, patients with Cushing's disease (CD) may represent a subgroup with prolonged impairment of sinonasal quality of life (QOL). We retrospectively identified patients with CD who underwent EEA at our institution. Control patients with non-functional tumors were matched by age, gender, and extent of EEA. The primary outcome was post-operative 22-item Sino-Nasal Outcome Test (SNOT-22) scores. Ten patients with CD met the selection criteria and 20 controls were selected for comparison. Nine of the CD patients achieved persistent endocrinologic remission post-operatively. Comparing the CD and control groups, there was no difference in post-operative SNOT-22 score at 1 or 3 months. At 6 months, SNOT-22 scores were significantly worse in the CD group (27.4 ± 21.6 vs. 2.8 ± 2.3, P = .039). SNOT-22 scores improved to normal from 1 to 6 months in the control cohort (P = .007), but not in the Cushing's group (P = .726). Morbidity was present across all SNOT-22 domains, but was highest in the sleep domain (P = .023). Only morbidity in the facial domain improved over time (P = .032). Patients with CD have significantly prolonged postoperative sinonasal QOL impairment following EEA compared to patients with non-functioning tumors, who normalize within 6 months. In CD patients, only morbidity in the facial domain, likely related to post-operative pain and nasal packing, improved over time, while the sleep domain was the most affected.