Background: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory disease of the nose and paranasal sinuses characterized by intense inflammation, decreased health-related quality of life (HRQoL), and in severe cases high frequency of co-morbidities and recurrence despite treatment. Conservative treatment consists of nasal lavage, intranasal corticosteroids, and courses of oral corticosteroids, and antibiotics in exacerbations. Endoscopic sinus surgery (ESS) and/or biological therapy is considered if appropriate conservative treatment is not sufficient. The optimal extent of ESS in recalcitrant CRSwNP is not known. The aim of this randomized controlled trial is to evaluate and compare the efficacy and safety of limited ESS with partial ethmoidectomy with extended ESS with total ethmoidectomy in patients with severe CRSwNP. Methods: AirGOs Operative is a randomized controlled trial. It is an investigator-driven multicenter trial led by Helsinki University Hospital. The two surgery arms are compared. The primary outcome is the change in the SNOT-22 score at the 12-month follow-up. Secondary outcomes include the change in the SNOT-22 score at 24-months follow-up, the changes in polyp score, Lund-Mackay (LM) CT score, health-related quality of life (HRQoL), loss of productivity, nasal patency (peak nasal inspiratory flow (PNIF) ± acoustic rhinometry (ARM), olfaction test (Sniffin’ Sticks, identification), lung function (spirometry and PEF) and findings in pathological analysis at 12/24-months follow-up. Discussion: AirGOs Operative trial will lead to a better understanding of the optimal extent of ethmoidectomy in the treatment of recalcitrant severe CRSwNP.