The bacterial flora of chronic maxillary sinusitis has been the subject of numerous investigation. Various techniques have been empolyed to obtain a representative specimen of maxillary sinusitis. The authors examined 44 patients of chronic maxillary sinusitis from December 1977 to July 1978 in Seoul National University Hospital and analysed bacterial strains and their sensitivity to antibiotics. The material for bacteriological examination have been obtained by antral puncture. 1) Among 44 patients, bacteria was isolated in 34 patients and the other were sterile. 2) Among 34 patients, 28 cases (82.4%) have single strain, 5 cases have two strains and 1 case has three strains. 3) Among 41 isolated strains, Hemophilus influenza was 14 strains (34.2%), Streptococcus 14 strains (34.2%), Staphylococcus 4 strains (9.8%). 4) Hemophilus influenza strains were sensitive to Penicillin, Ampicillin, Cephalosporin, Gentamycin. 5) Streptococcus strains were sensitive to Chloramphenicol, Penicillin, Gentamycin, Cephalosporin.