In the microbiological study of chronic faucial tonsillitis, there were a lot of reports by many investigators. But the distribution of microorganisms was so variable, the results revealed many differences according to the each investigator. Author had studied for 123 patients who admitted for tonsillectomy from October, 1979 to August, 1980 at the Dept. of E.N.T., Kyung Hee University hospital. We performed direct smear and cultrue of the materials which were taken by swab on the surface of both palatine tonsils before tonsilectomy and squeezing of cut surface of tonsils after tonsillectomy. And then, the relationship between each microorganism and A.S.O. titer was investiagted. The results were as follows. 1) On the surface culture, 159 strains were isolated from 116 tonsils. Among them, α-Hemolytic streptococcus was most frequently isolated, 63 strains (39.6%). Neisseria catarrhalis, 60 strains (37.1%) and staphylococcus aureus 26 strains (16.4%) were next in order. 2) On the cut surface culture, 133 strains were isolated from 115 tonsills. Among them, Neisseria catarrhalis was most frequently isoated, 50 strains (37.6%). α-Hemolytic streptococci 34 strains (25.6%) and staphylococcus aureus 33 strains (24.8%) were next in order. 3) In 66 cases (53.7%), same bacteria were cultured on surface and deep tissues at times. Mixed infection was 42 cases (34.1%) on surface culture and 25 cases (20.3%) on cut surface culture. 4) In sensitivity test for Staphylococcus aureus (35 cases), cephalosporin, cloxacillin, minocin, lincocin, erythromycin, amiktam were noted to be susceptible, and penicillin, terramycin ampicillin were noted to be resistant. For hemolytic streptococci, cephalosporin, cloxacillin, erythromycin, limcocin, amiktam were noted to be susceptible, and ampicillin, terramycin, penicillin were noted to be resistant. 5) In estimation A.S.O. titer, the elevation of serum A.S.O. level was found in all four cases with β-Hemolytic streptococci. But the elevation of serum A.S.O. level in remaining cases with α-Hemolytic streptococci and other bucteria was not remarkable.