Immunohistochemical staining for keratin proteins may be useful as a diagnostic parameter in head and neck neoplasms. Our study evaluates the keratin antibody staining properties of 27 samples of normal tissues and squamous cell carcinoma of the vocal folds after surgical removal. In normal epithelia, low molecular weight cytokeratins were strongly positive in basal layer but apparently reduced in suprabasal layers and completely negative in superficial layer. In invasive squamous cell carcinomas, low molecular weight anti-CK Ab were positive in all carcinoma cells of poorly differentiated carcinomas. On the other hand, high molecular weight anti-CK Ab were positive in almost all carcinoma cells of well differentiated carcinomas.