A 61-year-old man was referred to our hospital because of rapid growth of a mass shadow revealed by chest radiography. The mass was diagnosed as pure small cell carcinoma by CT-guided needle biopsy, and the patient underwent chemotherapy. However, as the tumor showed no response, we considered the possibility of some other form of malignancy and performed surgery. Postoperatively, the mass was diagnosed as small cell carcinoma combined with small cell, spindle cell and squamous cell carcinoma. We report this case in view of the rarity of this combination of morphologic patterns in a primary bronchogenic carcinoma.