Swabs from 93 chronically inflamed maxillary sinuses in children mere taken from aerobic and anaerobic bacteria during endoscopy. Bacterial growth was present in 87/93 specimens (93%). Anaerobic bacteria were isolated in 81/87 culture-positive specimens (93%) and mere recovered alone in 61 cases (70%) and mixed with aerobic or faculative bacteria in 20 (23%). Aerobic or facultative bacteria were present alone in six cases (7%). A total of 261 isolates (3/specimen), 19 (2.4/specimen) anaerobes and 69 (2.6/specimen) aerobes or facultatives, were isolated. The predominant anaerobic organisms sere Bacteroides sp. and anaerobic cocci; the predominant aerobes or facultatives mere Streptococcus sp. and Staphylococcus aureus. These findings indicate the important role of anaerobic organisms in chronic sinusitis.