Primary pulmonary choriocarcinoma is an extremely rare tumor in men, with 13 cases reported in the literature. Due to its rarity, primary choriocarcinoma of the lung in men is often incorrectly diagnosed as more common diseases, such as primary or metastatic lung cancer, and therefore potentially curative chemotherapy or surgery may be withheld from the patient. In this report, we present the case of a 23-year-old man with hemoptysis and progressive dyspnea. Airspace consolidation with multiple nodules of varying sizes was found on a chest radiograph. The results of a urine pregnancy test were positive, and the beta-human chorionic gonadotropin level was markedly elevated both in the serum and the urine. Subsequently, testing of a bronchoscopic biopsy specimen proved these tumors to be choriocarcinoma. We conclude that the urine pregnancy test, a simple and convenient method, would be very useful in the rapid diagnosis of primary pulmonary choriocarcinoma in men.