Gynecomastia with mastodynia and galactorrhea as a paraneoplastic syndrome due to lung cancer with complete response after surgical excision is rare. A 62-year-old Caucasian male presented with mastodynia, galactorrhea and right breast enlargement. Chest x-ray revealed a left upper lobe tumor. The patient had high levels of serum beta-human chorionic gonadotropin (b-HCG) and prolactine. Complete staging was negative for metastases. A typical left upper lobectomy with radical mediastinal lymph node dissection was performed. Pathology report was consistent with a poorly differentiated adenocarcinoma (T2N1M0). Immunohistochemically, multinucleate cells and occasional mononucleate tumor cells showed positivity for human chorionic gonadotropin. The patient received adjuvant chemotherapy with cisplatin - navelbine. One year later physical examination showed regression of both gynecomastia and mastodynia and there was no nipple discharge, while he is free from local or distant metastatic disease and the b-HCG level is normal (1,59 mIU/ml). This case represents a very rare, first manifestation of lung cancer. Galactorrhea, mastodynia and gynecomastia were the initial symptoms, which totally resolved following the successful surgical resection and adjuvant chemotherapy. In this case, prolactin and b-HCG are useful biomarkers during follow up for checking local or distal recurrence of the disease.