The aerobic and anaerobic microbiology and management of 69 children who had chronic suppurative otitis media were studied retrospectively. A total of 188 isolates (103 anaerobic and 85 aerobic) were recovered. Anaerobic organisms alone were isolated from 11 (16%), aerobic bacteria only in 21 (30%) and mixed aerobic and anaerobic flora was present in 37 (54%). Forty-five beta-lactamase-producing bacteria were recovered from 60 (58%) patients. The most rapid time for resolution was noticed with clindamycin (8.3 +/- 0.6 days) (P < 0.001), as compared with ampicillin (12.0 +/- 0.8 days), erythromycin (16.5 +/- 1.6 days) and cefaclor (14.6 +/- 2.3 days). Resolution of the infection was achieved in 16 of 20 (80%) of those treated with clindamycin, 12 of 24 (50%) treated with ampicillin, 6 of 13 (46%) treated with erythromycin, and 4 of 12 (33%) treated with cefaclor. Organisms resistant to the antimicrobial used were recovered in 26 of 31 of patients who failed to respond to therapy. These findings indicate the role of resistant aerobic and anaerobic organisms in the polymicrobial etiology of chronic otitis media in children and illustrate the superiority of therapy effective against anaerobic bacteria.