We assayed the estrogen and progesterone cytosolic receptors by using the enzyme immunoassay method, the epidermal growth factor (EGF) cell surface receptors by using 125I-labeled hormone, and the levels of polyamines (putrescine, spermine, and spermidine) by using a high-pressure liquid chromatography (HPLC) procedure in neoplastic and surrounding normal tissues of patients with colorectal cancer. Our findings show that mean polyamine levels in neoplastic tissue were approximately two-fold greater than the levels in normal colonic mucosa. Estrogen and progesterone receptorial content in normal mucosa were twofold greater than those in neoplastic tissue. No significant differences in EGF receptors were found between colonic cancer tissue and the surrounding normal tissues. The correlations we found between 1) estrogen and polyamine levels and 2) estrogen and EGF binding suggest the existence of a modulation of the estrogens on colonic mucosa cell proliferation. Furthermore, there was no significant dependency of polyamine and receptor concentrations from the tumor site, the histologic differentiation, or the age and sex of patients.