The expression of c-erbB-1 and c-erbB-2 oncogenes were investigated by immunohistochemistry using monoclonal antibodies to c-erbB-2 and c-erbB-2 protein in 43 cases of basal cell carcinoma （BCC） and 26 cases of squamous cell carcinoma （SCC）. We found that the expression of c-erbB-1 oncogene in all BCC increased by different degrees and the expression of c-erbB-2 oncogene in BCC was significantly reduced or lost when compared to that in normal epidermal cells. Furthermore

apparent negative and positive rela-tionships were observed respectively between the tumor differentiation and the expression of cerbB-1 and c-erbB-2 oncogenes in SCC. It is suggested that the abnormal expression of c-erbB-1 and c-erbB-2 oncogenes in BCC and SCC may play a role in the development of skin tumors. The pattern of the c-erbB-1 and c-erbB-2 oncogenes expression in SCC may assist in distinguishing the biological behavior and prognosis of SCC.