Altered expression of growth factors and growth factor receptors is frequently described in human tumors and human tumor cell lines. This further supports the hypothesis that oncogenesis is due to the subversion of mitogen-responsive pathways. The aim of this study was to investigate the expression of epidermal growth factor receptor (EGFR) and transforming growth factor alpha (TGF alpha) in 13 larynx carcinomas and 2 carcinomas of the oral cavity. We found receptor overexpression in 7 out of 15 tumors at mRNA and/or protein level but low expression in the majority of the normal adjacent tissues. TGF alpha was expressed only in 1 case, but no tyrosine kinase activity of the receptor was detected by antiphosphotyrosine antibody.