We studied the bacteriology ofmaxillary sinus aspirates obtain ed from patients diagnosed with chronic sinusitis. We recovered 659 strains from 510 aspirates; of these, 572 (86.8 %) were aerobes and 87 (13.2 %) were anaerobes. Aerobes only were recovered from 310 of the 510 specimens (60.8%) and anaerobes only from 31 (6.1 %). Among the 572 aerobic bacteria, the most prevalent organisms were Streptococcus viridans (158 strains [27.6%]), Streptococcus pneumoniae (67 [11 .7 %}), Corynebacterium species (66 [11 .5 %]), Staphylococcus aureus (54 [9.4%]), Moraxella catarrhalis (38 [6.6%]), Hemophilus parainfluenzae (33 [5.8%]), and group C beta-hemolytic streptococci (26 [4.5%]). Amon g the 87 recovered anaerobes were species ofPep tostreptococcus (32 strains [36.8 %]), Prevotella (22 [25.3 %]), Actinomyces (13 [14.9 %]), Propionibacterium (11 [12.6%]), Fusobacterium (8 [9 .2 %]), and Veillonella (l [1.1%]). Beta-lactamase p roduction was detected in 115 ofthe 572 aerobic strains (20.1 %) and in 10 of the 87 anaerobic strains (11.5 %). Wefound that the prevalence and type of organisms we identified in chronic sinusitis did not differ substantiallyfrom those reported in pr evious studies. Our study is one ofthe more extensive reports on the type and prevalence ofpathogens in chronic sinusitis that has been publ ished to date.