The objective of the study was to compare the proportions of the recovery of pathogens of acute maxillary sinusitis in adults in the 4-year period prior to the 5-year period that followed the introduction of vaccination of children with the 7-valent pneumococcal vaccine (PCV7). Cultures were obtained through endoscopy from 385 adults with acute maxillary sinusitis, 156 between 1997 and 2000, and 229 between 2001 and 2005. One hundred and seventeen potentially pathogenic organisms were isolated from the cultures obtained between 1997 and 2000. The predominant organisms were Streptococcus pneumoniae (54 or 46 % of all isolates), Haemophilus influenzae non-type b (42 or 36 %), Moraxella catarrhalis (7 or 6 %), Streptococcus pyogenes (8 or 7 %) and Staphylococcus aureus (6 or 5 %). One hundred and sixty-seven potentially pathogenic organisms were isolated from the cultures obtained between 2001 and 2005. The most predominant organisms were H. influenzae non-type b (71 or 43 % of all isolates), Strep. pneumoniae (58 or 35 %), M. catarrhalis (13 or 8 %), Strep. pyogenes (12 or 7 %) and Staph. aureus (13 or 8 %). Significant statistical differences were noted in the rates of recovery of H. influenzae non-type b (P < 0.05) and Strep. pneumoniae (P < 0.05). A decrease occurred in the recovery of Strep. pneumoniae resistant to penicillin from 41 to 29 %, and an increase was noted in the isolation of beta-lactamase-producing H. influenzae from 33 to 39 %; however, neither change was statistically significant. These data illustrate that a significant shift occurred in the causative pathogens of acute maxillary sinusitis in adults in the 5 years after the introduction of vaccination of children with the PCV7 compared to the previous 4 years.