The authors reported a case of a 56-year-old man with lung cancer which secreted human growth hormone (hGH). On admission, he had clubbed fingers and gonalgia without complaining cough or sputum. Serological examination revealed a high level of hGH which was 22.7 ng/ml (normal < 1.46). Right upper lobectomy was performed in February, 1994. It returned to the normal level after resection of the tumor. Gonalgia was improved but he still had clubbed fingers after operation. Histological examination of the tumor shows poorly differentiated adenocarcinoma with no evidence of lymph node metastasis. Immunohistochemical study showed that a group of the tumor cells demonstrated a specific reaction for anti-hGH antibody.