Objective To assess the efcacy of newly designed butterfy splint with special technique for middle turbinate stabilization in preventing adhesion following bilateral endoscopic sinus surgery (ESS) for chronic rhinosinusitis with nasal polyps (CRSwNP). Study design Prospective, double-blind, randomized controlled. Setting University hospitals. Methods Following ESS, in cases of traumatized and/or unstable middle turbinates, newly designed butterfy plastic splint was randomly inserted in the middle meatus of one nasal side, while no splint was inserted in the other (control). Patients were followed up on after 1 week, 1 month, and 6 months. Endoscopic examination and a visual analog scale were used to evaluate each side of the nasal cavity for adhesion, crusting, pus, pain, nasal obstruction, and nasal discharge. Results Thirty patients (60 nasal sides) were included. For all investigated parameters, there was no signifcant diference between the splinted and non-splinted sides at the frst week visit. Adhesion was found signifcantly less in the splinted sides (3%) than the non-splinted sides (27%) after 1 month (P=0.038). The adhesion rate in the splinted sides remained 3% at the 3 month follow-up visit, however, in the non-splinted sides, the rate increased up to 30% (P=0.007). Throughout the follow-up visits, all other investigated parameters remained statistically insignifcant between both sides. Conclusions The newly designed butterfy plastic splints to avoid middle turbinate adhesion is safe and efective in both reducing middle meatal adhesion with low complication rate in CRSwNP patients undergoing ESS and middle turbinate stabilization in its intermediate position.