Subcellular distribution of c-myc oncogene product and EGF receptor in oral squamous cell carcinomas was examined by using immunohistochemical method. Immunohistochemy for c-myc oncogene showed three staining patterns. Reactive products were demonstrable in the nucleus, in the perinuclear cytoplasm with granular appearance and in the entire cytoplasm. Concomitant stainings of each reactive pattern were observed. Occasionally, the reactive product was strongly deposited on the chromatin under mitotic phase. EGF receptor positive cases were found in only 4 of 28 cases. Though reactive products were usually found in the cytoplasm, the cell surface staining was detected in the only one case. In this case, cells under mitotic phase were strongly stained. The fact that the strong staining both of c-myc and EGF receptor in cells under mitotic phase suggested the close relation between the expression of these genes and the proliferation of carcinoma cells.