PURPOSE: Blowout fracture is an outward fracture of the orbital wall. That usually occurs at inferior or medial wall of the orbit. The main pathophysiology is high intraocular pressure derived from impact of trauma. Among the four orbital wall, the medial wall is thinnest and most vulnerable to trauma. Many kinds of methods were introduced for correction of medial orbital wall fracture. Recently, transnasal endoscopic reconstruction methods were widely used. Endoscopic methods had many advantages. However, we experienced some cases of postoperative maxillary sinusitis. This study was planned to find out the effectiveness of middle meatal antrostomy after endoscopic reconstruction of medial orbital wall fracture. METHODS: This study was retrospective analysis of 28 patients who underwent transnasal endoscopic repair of medial orbital wall fracture. The 18 male and 10 female patients were ranged from 17 to 57 years of age(mean, 30.9 years). Among 28 patients, randomly selected 17 patients underwent middle meatal antrostomy as additional procedure by the same surgeon. After at least 12 months of follow-up period, we examined the nasal symptom, endoscopic and CT findings. RESULTS: One patient complained of nasal obstruction in middle meatal antrostomy group and four patients complained nasal symptoms in non middle meatal antrostomy group. On the endoscopic findings, three patients of non middle meatal antrostomy group had continuous nasal discharge. But middle meatal antrostomy group had no abnormal endoscopic findings. The abnormal CT finding(abnormal mucosal hypertrophy) were detected in four patient of non middle meatal antrostomy group. There were no abnormal CT findings in middle meatal antrostomy group. The data were statistically significant at comparative study. CONCLUSION: Authors think that the middle meatal antrostomy has some advantages as a additional procedure of endoscopic reconstruction of medial orbital wall fracture. Especially, it is good at preventing post- operative maxillary sinusitis. But, more larger group and strict application of disease entity are need for correct evaluation of middle meatal antrostomy effect.