An analysis of 902 cases of diagnostic biopsy that was performed at ENT outpatient clinic of Seoul National University Hospital during past 5 years was made to evaluate general incidence of biopsy, rate of misdiagnosis and rebiopsy, distribution of benign and malignant lesions. The results are as follows. 1) Among 26,394 new outpatients during 5 years, 902 cases of diagnostic biopsy(3.4%) was performed. Male cases were 595(66%), female cases were 307(34%). 2) Histopathological diagnosis of 902 cases is nonspecific inflammation 283 cases(31.4%) specific inflammation 50 cases(5.6%), benign lesion 232 cases (25.7%), malignancy 311 cases(34.5%). 3) Overall rate of misdiagnosis was 13.3%, including esophagus 29.4%, nasopharynx 24.2%, mouth floor 17.7%, nose and paranasal sinuses 14.6%, faucial tonsil 14.5% in order. 4) Overall rate of rebiopsy was 2.9% including esophagus 11.8%, palate 6.5%, oropharynx 4.0%, Larynx 4.0%, tongue 3.5% in order. 5) The incidence of benign lesion was polyp 29.3%, nodule 15.1%, papilloma 12.5%, hemangioma 9.9% in order. 6) The incidence of malignant lesion is squamous cell Ca. 71.1%, malignant lymphoma 8.4%, undifferentiated Ca. 7.7%, adenoid cystic Ca. 1.6%, malignant melanoma 1.6%, in order.