Human lung giant cell carcinoma cell strains were implanted into the lungs of nude mice via an intrabronchial procedure. Tumorigenicity, invasion and metastasis of the xenografts, and their morphological features, including the findings by light and electronic microscopy and immunohistochemistry were investigated. Dissemination of xenografts within the airway (2/8), invasion to diaphragm (5/8), and development of bloody hydrothorax (5/8), were discovered. Metastasis via lymphatic and blood vessel routes as well as seeding metastasis occurred in all the tumor-bearing animals. The morphological features of xenografts were consistent with those of the parental giant cell carcinoma. These results indicate that lung cancer cell strains grow autonomously and the behavior of invasion and metastasis of the xenografts imitates more closely the clinical manifestation of lung cancer than their subcutaneous counterparts. Since microenvironment influences the biological behavior of the transplants, this model seemed to be more ideal for further investigation experimentally.