To investigate whether sex hormone receptors exist in the resected non-small-cell lung cancer in human beings and to determine a link between the pulmonary carcinogenesis and the sex receptor status of the lung cancer tissue, we reviewed the case histories of 64 patients who underwent resectional therapy for non-small-cell lung cancer between 1988 and 1990 (38 men and 26 women, mean age 65 years). Mouse monoclonal immunoglobulin G antibodies were used for immunohistochemical detection of estrogen receptors and progesterone receptors in the acetone-fixed specimen. The control group consisted of normal lung tissue from the patients with and without bronchogenic carcinoma and breast cancer tissue from the patients with estrogen and progesterone receptor immunoreactivity. No evidence of estrogen and progesterone receptor immunoreactivity was present in the normal lung tissue. All but two patients had immunoreactivity (97%) for estrogen receptors in the lung cancer tissue (p < 0.001). The differences for sex and for histologic subtypes were not statistically significant. Observed actuarial survival at 3 years was 83% for all patients with estrogen receptor immunoreactivity: 94% for women and 75% for men (p < 0.05). We found no correlation between the hormone receptor status and the type, clinical features, or prognosis of the non-small-cell lung cancer. We conclude that an abundance of estrogen receptors is hosted only in cancerous tissue, not in normal pulmonary tissue. Improved identification and definition of estrogen receptors in the nontarget lung cancer tissue offer a possibility of antiestrogen therapy for patients with advanced bronchogenic carcinoma.