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Epidermal growth factor (EGF) stimulates the growth of several types of epithelial tissues and possesses a strong mitogenic activity that is mediated through its cell surface receptor (EGFR). The aim of this study was to characterize EGFR and measure its levels in head and neck tumors biopsies (70 patients); use of a simplified competition technique with a radiolabeled ligand allowed evaluation of functional EGFR. Five samples (4 tumors and 1 control) were used to characterize EGF binding. Graphic representation identified a single family of binding sites. K_d values revealed high affinity for EGF binding: mean K_d, 0.156/pm 0.108 nM (0.095‐0.347 nM). EGF‐binding characteristics (K_d) were similar in nontumoral tissue samples (controls) and in tumor material. In 59 of 60 cases, EGFR levels were higher in the tumor than in the corresponding controls. A significant correlation was found between EGFR levels and …