The purpose of this study was to investigate the extent of pediatric sinusitis, treatment results and prognosis, and the pattern of recovery by OMU CT scan. We analysed 55 pediatric sinusitis patients(105 sinuses) by OMU CT scan and had treated them with medication and sinus irrigation untill clear sinus was seen. Treatment results were evaluated by sinus irrigation, Waters' view and OMU CT scan. Results were as follows ; 1) Pansinusitis was the most common(63.8%), maxillary sinusitis was in 19.2%, 13.3% showed maxillary sinusitis with ethmoiditis on OMU CT scan. 2) After medication and continuous sinus irrigation, 44.8% of pediatric sinusitis were cured, 25.7% improved and 29.5% aggravated or failed. 3) Ethmoiditis improved in 88.5% among 26 anterior ethmoid sinusitis, but recovery rates of maxillary sinusitis was less than that of ethmoiditis. Therefore, ethmoiditis without ostiomeatal abnormalities responded very well to the conservative treatment so that maxillary sinus might be a key area to be focused in pediatric sinusitis and repeated sinus irrigation could be effective in the management of pediatric sinusitis, especially in the cases that scanty pus accumulated in spite of persistent sinus irrigation. OMU CT scan was essential to evaluate the extent of disease.