198 cases of tonsillectomy and adenoidectomy were performed at Seoul National University Hospital from the period of Jan. 1972 to June 1975. All the patients were in the age of 3 years to 13 years old. Authors studied the clinical and histopathological view points of these patients and obtained following results. 1) During this period of Jan. 1972, total 1,637 patients were admitted to ENT department. Among them T & A cases were 12%. 2) Male : Female ratio was 2 : 1, predominent in male. 65% out of total patients were in the age group of 6 to 9 years. 3) The most frequently complained problem was frequent URI and sore throat (63%), hearing disturbance (14%), mouth breathing (12%), rhinorrhea (6%) and others (5%) in order. 4) 94 cases out of total patients (48%) had inflammatory change in the middle ear or in the nasal cavity and sinuses. 5) Tonsillar hypertrophy over () was noted in 85% of total patients. 6) Leucocytosis over 10,000/mm³ was noted in 22% of total patients and average total protein level was higher (7.4 gm%) than normal level (6.88+0.94 gm%). 7) Pure tone audiograms were taken from 15 patients who complained of hearing disturbance. 12 out of 15 cases had bilateral conductive hearing loss in mild to moderate degree. 8) Histopathological findings revealed lymphoid hyperplasia with increased germinal center activity in almost all cases and inflammatory cell infiltration was more marked in accompaniment with mucosal ulceration and small crypt abscess formation. In half of the cases there was mild to moderate degree of fibrosis.