Twenty-two children with chronic tonsillitis or adenoid enlargement were studied regarding the bacterial flora of their maxillary sinuses. The puncture of maxillary sinus was performed at surgery(adenoidectomy and/or tonsillectomy) and aspirates were cultured. Their sinus radiographs(Waters' view) were reviewed by two pediatric radialogists without any information. Twenty-four bacterial organisms were isolated from 19 patients(86.3%), and the most common organism was Streptococcus viridans(50%). The 13(92.9%) of 14 patients who showed abnormal maxillary yinus radiographs revealed positive culture, but the 6(31.6%) of 19 patients who revealed positive culture showed normal maxillary sinus radiographs. We concluded that children with abnormal maxillary sinus radiographs had bacterial infection in almost all patients, but we had to improve the method of aseptic culture technique and the problems of underdiagnosis or false negative radiologic image.