Collagen type IV expression of the basement membrane zone(BMZ) of the epithelium of benign lesions of the vocal folds was inverstigated immunohisto-chemically in 26 patients suffering from various benign laryngeal disease such as vocal nudule, vocal polyp, sulcus vocalis, and intubation granuloma. Characteristic patterns of immunostaining of benign vocal folds lesion were recognized. Vocal nodule and sulcus vocalis were showed weak and thick stained collagen type IV band, indicating BMZ injury. Vocal polyp was showed continuous linear pattern of collagen type IV band, indicating intact the basement membrane(BM) and intubation granuloma was absent collagen type IV band, indicating no formation of the BM. Therefore there are suggested the main pathologic response sites of vocal nodule and sulcus vocalis are the BM and the connecting links of the basal cell layer and basement memebrane zone, and of vocal polyp is sub-basement memebrane area between the BM and superficial layer of the lamina propria. The expression pattern of collagen type IV in the BMZ of benign vocal fold lesions of increased not only our understanding of the pathophysiology of benign vocal fold lesion but clear differentiation of them.