Recent studies have demonstrated that the amount of epidermal growth factor receptor (EGF-R) is increased in squamous cell carcinoma cells and that the amino acid sequence of EGF-R shows great homology with the v-erb B transforming protein. In this study, we examined the tissue localization of EGF-R and myc oncogene product in normal squamous epithelium, dysplasia, carcinoma in situ, invasive squamous cell carcinoma of the uterine cervix and in metastatic lymph nodes by means of the avidin/biotin immunoperoxidase technique. Normal squamous epithelium was negative for EGF-R and myc product. The lesions of dysplasia and carcinoma in situ had a positive staining for EGF-R, but were still negative for myc product. There were differences in the staining intensity of EGF-R and myc product among the types of invasive carcinoma. Staining for EGF-R and myc product was negative in small cell non-keratinizing carcinoma, whereas strong staining for both EGF-R and myc product was observed in large cell non-keratinizing and keratinizing carcinoma. The intensity of positive staining for EGF-R and myc product declined in the lesions of cancer pearl. Metastatic lymph nodes were remarkably stained for EGF-R and myc product, while non-metastatic lymph nodes were negative for EGF-R and myc product. Our observations suggest that the amplified expression of EGF-R and myc product may accompany the malignant transformation of squamous epithelium of the uterine cervix, together with the metastasis.